Deleting user fails while setting author_id in the database

Summary

When a user attempted to delete their user account to re-use an email address. However, the deletion failed and the user just became blocked and stalled out during this process. I changed the email address and appended _old so they can re-use their email address. However, we should still delete their user old account. I tried deleting it via Admin but it timed out.
Steps to reproduce

Example Project

Details can be found in this issue. (internal)
Kibana: https://log.gprd.gitlab.net/goto/3db3c5e0-b065-11ec-b73f-692cc1ae8214 (internal)
Zendesk: https://gitlab.zendesk.com/agent/tickets/277846 (internal)
What is the current bug behavior?

When a user tries to remove his account, it fails.
It fails even when trying to remove from the admin area.
It also fails when we test the same from console.
What is the expected correct behavior?

It should delete the user.
Relevant logs and/or screenshots

Error log
[ gprd ] production> Users::DestroyService.new(User.find_by_username('ADMINUSER')).execute(u)
D, [2022-03-31T11:20:32.323280 #3413723] DEBUG -- :   User Load (1.9ms)  /*application:console,db_config_name:main*/ SELECT "users".* FROM "users" WHERE (LOWER("users"."username") IN (LOWER('TKMA4CU'))) LIMIT 1
D, [2022-03-31T11:20:32.333947 #3413723] DEBUG -- :   Member Load (1.6ms)  /*application:console,db_config_name:main*/ SELECT "members".* FROM "members" WHERE "members"."user_id" = 8306233 ORDER BY "members"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.339501 #3413723] DEBUG -- :   Project Load (1.7ms)  /*application:console,db_config_name:main*/ SELECT "projects"."id", "projects"."name", "projects"."path", "projects"."description", "projects"."created_at", "projects"."updated_at", "projects"."creator_id", "projects"."namespace_id", "projects"."last_activity_at", "projects"."import_url", "projects"."visibility_level", "projects"."archived", "projects"."merge_requests_template", "projects"."star_count", "projects"."merge_requests_rebase_enabled", "projects"."import_type", "projects"."import_source", "projects"."avatar", "projects"."approvals_before_merge", "projects"."reset_approvals_on_push", "projects"."merge_requests_ff_only_enabled", "projects"."issues_template", "projects"."mirror", "projects"."mirror_user_id", "projects"."shared_runners_enabled", "projects"."runners_token", "projects"."build_coverage_regex", "projects"."build_allow_git_fetch", "projects"."build_timeout", "projects"."mirror_trigger_builds", "projects"."public_builds", "projects"."pending_delete", "projects"."last_repository_check_failed", "projects"."last_repository_check_at", "projects"."only_allow_merge_if_pipeline_succeeds", "projects"."has_external_issue_tracker", "projects"."repository_storage", "projects"."request_access_enabled", "projects"."has_external_wiki", "projects"."repository_read_only", "projects"."lfs_enabled", "projects"."description_html", "projects"."only_allow_merge_if_all_discussions_are_resolved", "projects"."repository_size_limit", "projects"."service_desk_enabled", "projects"."printing_merge_request_link_enabled", "projects"."auto_cancel_pending_pipelines", "projects"."cached_markdown_version", "projects"."last_repository_updated_at", "projects"."ci_config_path", "projects"."disable_overriding_approvers_per_merge_request", "projects"."delete_error", "projects"."storage_version", "projects"."resolve_outdated_diff_discussions", "projects"."remote_mirror_available_overridden", "projects"."only_mirror_protected_branches", "projects"."pull_mirror_available_overridden", "projects"."jobs_cache_index", "projects"."external_authorization_classification_label", "projects"."mirror_overwrites_diverged_branches", "projects"."external_webhook_token", "projects"."pages_https_only", "projects"."packages_enabled", "projects"."merge_requests_author_approval", "projects"."pool_repository_id", "projects"."runners_token_encrypted", "projects"."bfg_object_map", "projects"."detected_repository_languages", "projects"."merge_requests_disable_committers_approval", "projects"."require_password_to_approve", "projects"."emails_disabled", "projects"."max_pages_size", "projects"."max_artifacts_size", "projects"."remove_source_branch_after_merge", "projects"."marked_for_deletion_at", "projects"."marked_for_deletion_by_user_id", "projects"."suggestion_commit_message", "projects"."autoclose_referenced_issues", "projects"."project_namespace_id", "projects"."hidden" FROM "projects" WHERE "projects"."mirror_user_id" = 8306233 ORDER BY "projects"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.345569 #3413723] DEBUG -- :   IncidentManagement::OncallRotation Load (1.1ms)  /*application:console,db_config_name:main*/ SELECT "incident_management_oncall_rotations".* FROM "incident_management_oncall_rotations" INNER JOIN "incident_management_oncall_participants" ON "incident_management_oncall_rotations"."id" = "incident_management_oncall_participants"."oncall_rotation_id" WHERE "incident_management_oncall_participants"."user_id" = 8306233 AND "incident_management_oncall_participants"."is_removed" = FALSE
D, [2022-03-31T11:20:32.348360 #3413723] DEBUG -- :   IncidentManagement::EscalationRule Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "incident_management_escalation_rules".* FROM "incident_management_escalation_rules" WHERE "incident_management_escalation_rules"."user_id" = 8306233
D, [2022-03-31T11:20:32.350314 #3413723] DEBUG -- :   IncidentManagement::EscalationRule Destroy (0.6ms)  /*application:console,db_config_name:main*/ DELETE FROM "incident_management_escalation_rules" WHERE 1=0
D, [2022-03-31T11:20:32.352781 #3413723] DEBUG -- :   User Load (1.1ms)  /*application:console,db_config_name:main*/ SELECT "users".* FROM "users" WHERE "users"."user_type" = 5 ORDER BY "users"."id" ASC LIMIT 1
D, [2022-03-31T11:20:32.364699 #3413723] DEBUG -- :   TRANSACTION (0.5ms)  /*application:console,db_config_name:main*/ BEGIN
D, [2022-03-31T11:20:32.366745 #3413723] DEBUG -- :   ResourceIterationEvent Load (1.6ms)  /*application:console,db_config_name:main*/ SELECT "resource_iteration_events"."id" FROM "resource_iteration_events" WHERE "resource_iteration_events"."user_id" = 8306233 ORDER BY "resource_iteration_events"."id" ASC LIMIT 1
D, [2022-03-31T11:20:32.370139 #3413723] DEBUG -- :   Epic Update All (1.2ms)  /*application:console,db_config_name:main*/ UPDATE "epics" SET "author_id" = 1243277 WHERE "epics"."id" IN (SELECT "epics"."id" FROM "epics" WHERE "epics"."author_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.373154 #3413723] DEBUG -- :   Epic Update All (1.7ms)  /*application:console,db_config_name:main*/ UPDATE "epics" SET "last_edited_by_id" = 1243277 WHERE "epics"."id" IN (SELECT "epics"."id" FROM "epics" WHERE "epics"."last_edited_by_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.375992 #3413723] DEBUG -- :   RequirementsManagement::Requirement Update All (1.2ms)  /*application:console,db_config_name:main*/ UPDATE "requirements" SET "author_id" = 1243277 WHERE "requirements"."author_id" = 8306233
D, [2022-03-31T11:20:32.380532 #3413723] DEBUG -- :   Vulnerabilities::Feedback Update All (2.8ms)  /*application:console,db_config_name:main*/ UPDATE "vulnerability_feedback" SET "author_id" = 1243277 WHERE "vulnerability_feedback"."author_id" = 8306233
D, [2022-03-31T11:20:32.383782 #3413723] DEBUG -- :   Vulnerabilities::Feedback Update All (0.9ms)  /*application:console,db_config_name:main*/ UPDATE "vulnerability_feedback" SET "comment_author_id" = 1243277 WHERE "vulnerability_feedback"."comment_author_id" = 8306233
D, [2022-03-31T11:20:32.386896 #3413723] DEBUG -- :   Issue Update All (1.5ms)  /*application:console,db_config_name:main*/ UPDATE "issues" SET "author_id" = 1243277 WHERE "issues"."id" IN (SELECT "issues"."id" FROM "issues" WHERE "issues"."author_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.389960 #3413723] DEBUG -- :   Issue Update All (1.9ms)  /*application:console,db_config_name:main*/ UPDATE "issues" SET "last_edited_by_id" = 1243277 WHERE "issues"."id" IN (SELECT "issues"."id" FROM "issues" WHERE "issues"."last_edited_by_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.392715 #3413723] DEBUG -- :   MergeRequest Update All (1.2ms)  /*application:console,db_config_name:main*/ UPDATE "merge_requests" SET "author_id" = 1243277 WHERE "merge_requests"."id" IN (SELECT "merge_requests"."id" FROM "merge_requests" WHERE "merge_requests"."author_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.395331 #3413723] DEBUG -- :   MergeRequest Update All (1.3ms)  /*application:console,db_config_name:main*/ UPDATE "merge_requests" SET "merge_user_id" = 1243277 WHERE "merge_requests"."id" IN (SELECT "merge_requests"."id" FROM "merge_requests" WHERE "merge_requests"."merge_user_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.398431 #3413723] DEBUG -- :   Note Update All (1.3ms)  /*application:console,db_config_name:main*/ UPDATE "notes" SET "author_id" = 1243277 WHERE "notes"."id" IN (SELECT "notes"."id" FROM "notes" WHERE "notes"."author_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.400755 #3413723] DEBUG -- :   AbuseReport Update All (0.9ms)  /*application:console,db_config_name:main*/ UPDATE "abuse_reports" SET "reporter_id" = 1243277 WHERE "abuse_reports"."reporter_id" = 8306233
D, [2022-03-31T11:20:32.402674 #3413723] DEBUG -- :   AwardEmoji Update All (0.7ms)  /*application:console,db_config_name:main*/ UPDATE "award_emoji" SET "user_id" = 1243277 WHERE "award_emoji"."user_id" = 8306233
D, [2022-03-31T11:20:32.406272 #3413723] DEBUG -- :   Snippet Update All (2.2ms)  /*application:console,db_config_name:main*/ UPDATE "snippets" SET "author_id" = 1243277 WHERE "snippets"."author_id" = 8306233 AND "snippets"."project_id" IS NOT NULL
D, [2022-03-31T11:20:32.409436 #3413723] DEBUG -- :   Review Update All (1.9ms)  /*application:console,db_config_name:main*/ UPDATE "reviews" SET "author_id" = 1243277 WHERE "reviews"."id" IN (SELECT "reviews"."id" FROM "reviews" WHERE "reviews"."author_id" = 8306233 LIMIT 100)
D, [2022-03-31T11:20:32.411187 #3413723] DEBUG -- :   TRANSACTION (0.7ms)  /*application:console,db_config_name:main*/ COMMIT
D, [2022-03-31T11:20:32.414258 #3413723] DEBUG -- :   User Load (1.1ms)  /*application:console,db_config_name:main*/ SELECT "users".* FROM "users" WHERE "users"."id" = 8306233 LIMIT 1
D, [2022-03-31T11:20:32.418029 #3413723] DEBUG -- :   Snippet Exists? (1.3ms)  /*application:console,db_config_name:main*/ SELECT 1 AS one FROM "snippets" WHERE "snippets"."author_id" = 8306233 LIMIT 1
D, [2022-03-31T11:20:32.422495 #3413723] DEBUG -- :   Key Load (1.8ms)  /*application:console,db_config_name:main*/ SELECT "keys".* FROM "keys" WHERE "keys"."user_id" = 8306233 AND ("keys"."type" IN ('LDAPKey', 'Key') OR "keys"."type" IS NULL) ORDER BY "keys"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.425645 #3413723] DEBUG -- :   PersonalAccessToken Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "personal_access_tokens".* FROM "personal_access_tokens" WHERE "personal_access_tokens"."user_id" = 8306233 ORDER BY "personal_access_tokens"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.429732 #3413723] DEBUG -- :   Identity Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "identities".* FROM "identities" WHERE "identities"."user_id" = 8306233 ORDER BY "identities"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.433471 #3413723] DEBUG -- :   U2fRegistration Load (1.5ms)  /*application:console,db_config_name:main*/ SELECT "u2f_registrations".* FROM "u2f_registrations" WHERE "u2f_registrations"."user_id" = 8306233 ORDER BY "u2f_registrations"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.436809 #3413723] DEBUG -- :   ChatName Load (1.2ms)  /*application:console,db_config_name:main*/ SELECT "chat_names".* FROM "chat_names" WHERE "chat_names"."user_id" = 8306233 ORDER BY "chat_names"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.439647 #3413723] DEBUG -- :   UsersStarProject Load (1.2ms)  /*application:console,db_config_name:main*/ SELECT "users_star_projects".* FROM "users_star_projects" WHERE "users_star_projects"."user_id" = 8306233 ORDER BY "users_star_projects"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.442623 #3413723] DEBUG -- :   Note Load (1.3ms)  /*application:console,db_config_name:main*/ SELECT "notes".* FROM "notes" WHERE "notes"."author_id" = 8306233 ORDER BY "notes"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.446006 #3413723] DEBUG -- :   Issue Load (1.1ms)  /*application:console,db_config_name:main*/ SELECT "issues".* FROM "issues" WHERE "issues"."author_id" = 8306233 ORDER BY "issues"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.448776 #3413723] DEBUG -- :   MergeRequest Load (1.0ms)  /*application:console,db_config_name:main*/ SELECT "merge_requests".* FROM "merge_requests" WHERE "merge_requests"."author_id" = 8306233 ORDER BY "merge_requests"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.520514 #3413723] DEBUG -- :   Subscription Load (69.9ms)  /*application:console,db_config_name:main*/ SELECT "subscriptions".* FROM "subscriptions" WHERE "subscriptions"."user_id" = 8306233 ORDER BY "subscriptions"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.523353 #3413723] DEBUG -- :   Doorkeeper::Application Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "oauth_applications".* FROM "oauth_applications" WHERE "oauth_applications"."owner_id" = 8306233 AND "oauth_applications"."owner_type" = 'User' ORDER BY "oauth_applications"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.526229 #3413723] DEBUG -- :   AbuseReport Load (1.2ms)  /*application:console,db_config_name:main*/ SELECT "abuse_reports".* FROM "abuse_reports" WHERE "abuse_reports"."reporter_id" = 8306233 ORDER BY "abuse_reports"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.530191 #3413723] DEBUG -- :   SpamLog Load (1.6ms)  /*application:console,db_config_name:main*/ SELECT "spam_logs".* FROM "spam_logs" WHERE "spam_logs"."user_id" = 8306233 ORDER BY "spam_logs"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.533167 #3413723] DEBUG -- :   AwardEmoji Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "award_emoji".* FROM "award_emoji" WHERE "award_emoji"."user_id" = 8306233 ORDER BY "award_emoji"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.535658 #3413723] DEBUG -- :   PathLock Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "path_locks".* FROM "path_locks" WHERE "path_locks"."user_id" = 8306233 ORDER BY "path_locks"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.537967 #3413723] DEBUG -- :   Approval Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "approvals".* FROM "approvals" WHERE "approvals"."user_id" = 8306233 ORDER BY "approvals"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.540243 #3413723] DEBUG -- :   Approver Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "approvers".* FROM "approvers" WHERE "approvers"."user_id" = 8306233 ORDER BY "approvers"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.542502 #3413723] DEBUG -- :   ProtectedBranch::MergeAccessLevel Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_merge_access_levels".* FROM "protected_branch_merge_access_levels" WHERE "protected_branch_merge_access_levels"."user_id" = 8306233 ORDER BY "protected_branch_merge_access_levels"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.544955 #3413723] DEBUG -- :   ProtectedBranch::PushAccessLevel Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_push_access_levels".* FROM "protected_branch_push_access_levels" WHERE "protected_branch_push_access_levels"."user_id" = 8306233 ORDER BY "protected_branch_push_access_levels"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.547805 #3413723] DEBUG -- :   ProtectedBranch::UnprotectAccessLevel Load (1.0ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_unprotect_access_levels".* FROM "protected_branch_unprotect_access_levels" WHERE "protected_branch_unprotect_access_levels"."user_id" = 8306233 ORDER BY "protected_branch_unprotect_access_levels"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.551720 #3413723] DEBUG -- :   TRANSACTION (0.5ms)  /*application:console,db_config_name:main*/ BEGIN
D, [2022-03-31T11:20:32.552941 #3413723] DEBUG -- :   Upload Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "uploads".* FROM "uploads" WHERE "uploads"."model_id" = 8306233 AND "uploads"."model_type" = 'User' AND "uploads"."uploader" IN ('PersonalFileUploader', 'NamespaceFileUploader', 'FileUploader') AND "uploads"."store" = 1 ORDER BY "uploads"."id" ASC LIMIT 1000
D, [2022-03-31T11:20:32.554973 #3413723] DEBUG -- :    (0.7ms)  /*application:console,db_config_name:main*/ SELECT "uploads"."path" FROM "uploads" WHERE "uploads"."model_id" = 8306233 AND "uploads"."model_type" = 'User' AND "uploads"."uploader" IN ('PersonalFileUploader', 'NamespaceFileUploader', 'FileUploader') AND "uploads"."store" = 2
D, [2022-03-31T11:20:32.556825 #3413723] DEBUG -- :   Upload Destroy (0.7ms)  /*application:console,db_config_name:main*/ DELETE FROM "uploads" WHERE "uploads"."model_id" = 8306233 AND "uploads"."model_type" = 'User' AND "uploads"."uploader" IN ('PersonalFileUploader', 'NamespaceFileUploader', 'FileUploader')
D, [2022-03-31T11:20:32.559720 #3413723] DEBUG -- :   Namespace Load (1.0ms)  /*application:console,db_config_name:main*/ SELECT "namespaces"."id", "namespaces"."name", "namespaces"."path", "namespaces"."owner_id", "namespaces"."created_at", "namespaces"."updated_at", "namespaces"."type", "namespaces"."description", "namespaces"."avatar", "namespaces"."membership_lock", "namespaces"."share_with_group_lock", "namespaces"."visibility_level", "namespaces"."request_access_enabled", "namespaces"."ldap_sync_status", "namespaces"."ldap_sync_error", "namespaces"."ldap_sync_last_update_at", "namespaces"."ldap_sync_last_successful_update_at", "namespaces"."ldap_sync_last_sync_at", "namespaces"."lfs_enabled", "namespaces"."description_html", "namespaces"."parent_id", "namespaces"."shared_runners_minutes_limit", "namespaces"."repository_size_limit", "namespaces"."require_two_factor_authentication", "namespaces"."two_factor_grace_period", "namespaces"."cached_markdown_version", "namespaces"."project_creation_level", "namespaces"."runners_token", "namespaces"."file_template_project_id", "namespaces"."saml_discovery_token", "namespaces"."runners_token_encrypted", "namespaces"."custom_project_templates_group_id", "namespaces"."auto_devops_enabled", "namespaces"."extra_shared_runners_minutes_limit", "namespaces"."last_ci_minutes_notification_at", "namespaces"."last_ci_minutes_usage_notification_level", "namespaces"."subgroup_creation_level", "namespaces"."emails_disabled", "namespaces"."max_pages_size", "namespaces"."max_artifacts_size", "namespaces"."mentions_disabled", "namespaces"."default_branch_protection", "namespaces"."unlock_membership_to_ldap", "namespaces"."max_personal_access_token_lifetime", "namespaces"."push_rule_id", "namespaces"."shared_runners_enabled", "namespaces"."allow_descendants_override_disabled_shared_runners", "namespaces"."traversal_ids" FROM "namespaces" WHERE "namespaces"."owner_id" = 8306233 AND "namespaces"."type" = 'User' LIMIT 1
D, [2022-03-31T11:20:32.574197 #3413723] DEBUG -- :    (1.2ms)  /*application:console,db_config_name:main*/ SELECT distinct(repository_storage) FROM "projects" WHERE "projects"."namespace_id" = 11150859 AND ("projects"."storage_version" < 1 OR "projects"."storage_version" IS NULL)
D, [2022-03-31T11:20:32.577927 #3413723] DEBUG -- :   Route Load (1.8ms)  /*application:console,db_config_name:main*/ SELECT "routes".* FROM "routes" WHERE "routes"."source_id" = 11150859 AND "routes"."source_type" = 'Namespace' LIMIT 1
D, [2022-03-31T11:20:32.579979 #3413723] DEBUG -- :   Route Destroy (0.7ms)  /*application:console,db_config_name:main*/ DELETE FROM "routes" WHERE "routes"."id" = 35068004
D, [2022-03-31T11:20:32.582809 #3413723] DEBUG -- :   RedirectRoute Load (1.5ms)  /*application:console,db_config_name:main*/ SELECT "redirect_routes".* FROM "redirect_routes" WHERE "redirect_routes"."source_id" = 11150859 AND "redirect_routes"."source_type" = 'Namespace'
D, [2022-03-31T11:20:32.586129 #3413723] DEBUG -- :   Project Load (1.5ms)  /*application:console,db_config_name:main*/ SELECT "projects"."id", "projects"."name", "projects"."path", "projects"."description", "projects"."created_at", "projects"."updated_at", "projects"."creator_id", "projects"."namespace_id", "projects"."last_activity_at", "projects"."import_url", "projects"."visibility_level", "projects"."archived", "projects"."merge_requests_template", "projects"."star_count", "projects"."merge_requests_rebase_enabled", "projects"."import_type", "projects"."import_source", "projects"."avatar", "projects"."approvals_before_merge", "projects"."reset_approvals_on_push", "projects"."merge_requests_ff_only_enabled", "projects"."issues_template", "projects"."mirror", "projects"."mirror_user_id", "projects"."shared_runners_enabled", "projects"."runners_token", "projects"."build_coverage_regex", "projects"."build_allow_git_fetch", "projects"."build_timeout", "projects"."mirror_trigger_builds", "projects"."public_builds", "projects"."pending_delete", "projects"."last_repository_check_failed", "projects"."last_repository_check_at", "projects"."only_allow_merge_if_pipeline_succeeds", "projects"."has_external_issue_tracker", "projects"."repository_storage", "projects"."request_access_enabled", "projects"."has_external_wiki", "projects"."repository_read_only", "projects"."lfs_enabled", "projects"."description_html", "projects"."only_allow_merge_if_all_discussions_are_resolved", "projects"."repository_size_limit", "projects"."service_desk_enabled", "projects"."printing_merge_request_link_enabled", "projects"."auto_cancel_pending_pipelines", "projects"."cached_markdown_version", "projects"."last_repository_updated_at", "projects"."ci_config_path", "projects"."disable_overriding_approvers_per_merge_request", "projects"."delete_error", "projects"."storage_version", "projects"."resolve_outdated_diff_discussions", "projects"."remote_mirror_available_overridden", "projects"."only_mirror_protected_branches", "projects"."pull_mirror_available_overridden", "projects"."jobs_cache_index", "projects"."external_authorization_classification_label", "projects"."mirror_overwrites_diverged_branches", "projects"."external_webhook_token", "projects"."pages_https_only", "projects"."packages_enabled", "projects"."merge_requests_author_approval", "projects"."pool_repository_id", "projects"."runners_token_encrypted", "projects"."bfg_object_map", "projects"."detected_repository_languages", "projects"."merge_requests_disable_committers_approval", "projects"."require_password_to_approve", "projects"."emails_disabled", "projects"."max_pages_size", "projects"."max_artifacts_size", "projects"."remove_source_branch_after_merge", "projects"."marked_for_deletion_at", "projects"."marked_for_deletion_by_user_id", "projects"."suggestion_commit_message", "projects"."autoclose_referenced_issues", "projects"."project_namespace_id", "projects"."hidden" FROM "projects" WHERE "projects"."namespace_id" = 11150859
D, [2022-03-31T11:20:32.589876 #3413723] DEBUG -- :   ChatTeam Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "chat_teams".* FROM "chat_teams" WHERE "chat_teams"."namespace_id" = 11150859 LIMIT 1
D, [2022-03-31T11:20:32.617668 #3413723] DEBUG -- :   Namespaces::UserNamespace Destroy (26.5ms)  /*application:console,db_config_name:main*/ DELETE FROM "namespaces" WHERE "namespaces"."id" = 11150859
D, [2022-03-31T11:20:32.619983 #3413723] DEBUG -- :   Key Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "keys".* FROM "keys" WHERE "keys"."user_id" = 8306233 AND ("keys"."type" IN ('LDAPKey', 'Key') OR "keys"."type" IS NULL)
D, [2022-03-31T11:20:32.622558 #3413723] DEBUG -- :   DeployKey Update All (0.8ms)  /*application:console,db_config_name:main*/ UPDATE "keys" SET "user_id" = NULL WHERE "keys"."type" = 'DeployKey' AND "keys"."user_id" = 8306233
D, [2022-03-31T11:20:32.624591 #3413723] DEBUG -- :   PersonalAccessToken Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "personal_access_tokens".* FROM "personal_access_tokens" WHERE "personal_access_tokens"."user_id" = 8306233
D, [2022-03-31T11:20:32.626361 #3413723] DEBUG -- :   Identity Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "identities".* FROM "identities" WHERE "identities"."user_id" = 8306233
D, [2022-03-31T11:20:32.628701 #3413723] DEBUG -- :   U2fRegistration Load (1.4ms)  /*application:console,db_config_name:main*/ SELECT "u2f_registrations".* FROM "u2f_registrations" WHERE "u2f_registrations"."user_id" = 8306233
D, [2022-03-31T11:20:32.630875 #3413723] DEBUG -- :   ChatName Load (1.2ms)  /*application:console,db_config_name:main*/ SELECT "chat_names".* FROM "chat_names" WHERE "chat_names"."user_id" = 8306233
D, [2022-03-31T11:20:32.632549 #3413723] DEBUG -- :   UsersStarProject Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "users_star_projects".* FROM "users_star_projects" WHERE "users_star_projects"."user_id" = 8306233
D, [2022-03-31T11:20:32.634582 #3413723] DEBUG -- :   ProjectAuthorization Destroy (0.7ms)  /*application:console,db_config_name:main*/ DELETE FROM "project_authorizations" WHERE "project_authorizations"."user_id" = 8306233
D, [2022-03-31T11:20:32.636147 #3413723] DEBUG -- :   Snippet Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "snippets".* FROM "snippets" WHERE "snippets"."author_id" = 8306233
D, [2022-03-31T11:20:32.637813 #3413723] DEBUG -- :   Note Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "notes".* FROM "notes" WHERE "notes"."author_id" = 8306233
D, [2022-03-31T11:20:32.639729 #3413723] DEBUG -- :   Issue Load (1.0ms)  /*application:console,db_config_name:main*/ SELECT "issues".* FROM "issues" WHERE "issues"."author_id" = 8306233
D, [2022-03-31T11:20:32.643205 #3413723] DEBUG -- :   MergeRequest Load (2.5ms)  /*application:console,db_config_name:main*/ SELECT "merge_requests".* FROM "merge_requests" WHERE "merge_requests"."author_id" = 8306233
D, [2022-03-31T11:20:33.591912 #3413723] DEBUG -- :   Event Destroy (947.0ms)  /*application:console,db_config_name:main*/ DELETE FROM "events" WHERE "events"."author_id" = 8306233
D, [2022-03-31T11:20:33.596935 #3413723] DEBUG -- :   Release Update All (3.4ms)  /*application:console,db_config_name:main*/ UPDATE "releases" SET "author_id" = NULL WHERE "releases"."author_id" = 8306233
D, [2022-03-31T11:20:33.652076 #3413723] DEBUG -- :   Subscription Load (53.9ms)  /*application:console,db_config_name:main*/ SELECT "subscriptions".* FROM "subscriptions" WHERE "subscriptions"."user_id" = 8306233
D, [2022-03-31T11:20:33.654370 #3413723] DEBUG -- :   Doorkeeper::Application Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "oauth_applications".* FROM "oauth_applications" WHERE "oauth_applications"."owner_id" = 8306233 AND "oauth_applications"."owner_type" = 'User'
D, [2022-03-31T11:20:33.657521 #3413723] DEBUG -- :   AbuseReport Load (1.8ms)  /*application:console,db_config_name:main*/ SELECT "abuse_reports".* FROM "abuse_reports" WHERE "abuse_reports"."user_id" = 8306233 LIMIT 1
D, [2022-03-31T11:20:33.659208 #3413723] DEBUG -- :   AbuseReport Load (0.8ms)  /*application:console,db_config_name:main*/ SELECT "abuse_reports".* FROM "abuse_reports" WHERE "abuse_reports"."reporter_id" = 8306233
D, [2022-03-31T11:20:33.661425 #3413723] DEBUG -- :   SpamLog Load (1.4ms)  /*application:console,db_config_name:main*/ SELECT "spam_logs".* FROM "spam_logs" WHERE "spam_logs"."user_id" = 8306233
D, [2022-03-31T11:20:33.663107 #3413723] DEBUG -- :   AwardEmoji Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "award_emoji".* FROM "award_emoji" WHERE "award_emoji"."user_id" = 8306233
D, [2022-03-31T11:20:33.665098 #3413723] DEBUG -- :   PathLock Load (0.9ms)  /*application:console,db_config_name:main*/ SELECT "path_locks".* FROM "path_locks" WHERE "path_locks"."user_id" = 8306233
D, [2022-03-31T11:20:33.666617 #3413723] DEBUG -- :   Approval Load (0.6ms)  /*application:console,db_config_name:main*/ SELECT "approvals".* FROM "approvals" WHERE "approvals"."user_id" = 8306233
D, [2022-03-31T11:20:33.668097 #3413723] DEBUG -- :   Approver Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "approvers".* FROM "approvers" WHERE "approvers"."user_id" = 8306233
D, [2022-03-31T11:20:33.669504 #3413723] DEBUG -- :   ProtectedBranch::MergeAccessLevel Load (0.6ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_merge_access_levels".* FROM "protected_branch_merge_access_levels" WHERE "protected_branch_merge_access_levels"."user_id" = 8306233
D, [2022-03-31T11:20:33.670883 #3413723] DEBUG -- :   ProtectedBranch::PushAccessLevel Load (0.6ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_push_access_levels".* FROM "protected_branch_push_access_levels" WHERE "protected_branch_push_access_levels"."user_id" = 8306233
D, [2022-03-31T11:20:33.672320 #3413723] DEBUG -- :   ProtectedBranch::UnprotectAccessLevel Load (0.7ms)  /*application:console,db_config_name:main*/ SELECT "protected_branch_unprotect_access_levels".* FROM "protected_branch_unprotect_access_levels" WHERE "protected_branch_unprotect_access_levels"."user_id" = 8306233
D, [2022-03-31T11:20:33.961500 #3413723] DEBUG -- :   User Destroy (288.4ms)  /*application:console,db_config_name:main*/ DELETE FROM "users" WHERE "users"."id" = 8306233
D, [2022-03-31T11:20:33.963366 #3413723] DEBUG -- :   TRANSACTION (1.1ms)  /*application:console,db_config_name:main*/ ROLLBACK
Traceback (most recent call last):
       16: from (irb):27
       15: from (irb):28:in `rescue in irb_binding'
       14: from ee/app/services/ee/users/destroy_service.rb:10:in `execute'
       13: from app/services/users/destroy_service.rb:68:in `execute'
       12: from lib/gitlab/database/load_balancing/connection_proxy.rb:70:in `transaction'
       11: from lib/gitlab/database/load_balancing/connection_proxy.rb:118:in `write_using_load_balancer'
       10: from lib/gitlab/database/load_balancing/load_balancer.rb:110:in `read_write'
        9: from lib/gitlab/database/load_balancing/load_balancer.rb:179:in `retry_with_backoff'
        8: from lib/gitlab/database/load_balancing/load_balancer.rb:112:in `block in read_write'
        7: from lib/gitlab/database/load_balancing/connection_proxy.rb:119:in `block in write_using_load_balancer'
        6: from lib/gitlab/database/load_balancing/connection_proxy.rb:60:in `block (2 levels) in <class:ConnectionProxy>'
        5: from lib/gitlab/database/load_balancing/connection_proxy.rb:118:in `write_using_load_balancer'
        4: from lib/gitlab/database/load_balancing/load_balancer.rb:110:in `read_write'
        3: from lib/gitlab/database/load_balancing/load_balancer.rb:179:in `retry_with_backoff'
        2: from lib/gitlab/database/load_balancing/load_balancer.rb:112:in `block in read_write'
        1: from lib/gitlab/database/load_balancing/connection_proxy.rb:119:in `block in write_using_load_balancer'
ActiveRecord::NotNullViolation (PG::NotNullViolation: ERROR:  null value in column "author_id" violates not-null constraint)
DETAIL:  Failing row contains (15565320, null, null, 28629009, null, null, null, null, null, null, 2021-08-11 16:30:07.844913+00, 2022-02-28 13:52:43.842638+00, null, null, 1, 7, 2, f, f, Secret Scanner: Possible Password Finding (Text: Password) v1.0...., Secret Scanner: Possible Password Finding (Text: Password) v1.0...., null, , 4, 1900549, null, null, null, null, null, null, f, t, 2021-08-11 16:30:07.839446+00).
CONTEXT:  SQL statement "UPDATE ONLY "public"."vulnerabilities" SET "author_id" = NULL WHERE $1 OPERATOR(pg_catalog.=) "author_id""
As from our intial investigation it looks like it is failing on updating Table "public.vulnerabilities" tagging relevant team members.
cc// @matt_wilson @thiagocsf
Implementation plan

Adjust app/services/users/migrate_to_ghost_user_service.rb to migrate Vulnerabilities to User.ghost
Adjust app/services/users/migrate_to_ghost_user_service.rb to migrate Vulnerabilities::ExternalIssueLinks to User.ghost
Edited May 17, 2022 by Michał Zając