Release version 2.6.0 Features: * Experimental support for CouchDB 2 has been added. Note: The data migration script is not compatible with CouchDB 2 and has to be run before an upgrade. Improvements: * Error handling and logging has been improved. It should now be easier to find the cause of problems. API error responses now contain the name of the `Exception` which caused the error. Further details for debugging purposes can be enabled with the new `api.expose-exception-messages` setting (Do NOT enable in production environments!). * Updated OAuth handling to restore compatibility with 3rd-party login services. Bug fixes: * Fixed multiple bugs caused by incorrect type handling in the database layer. * Fixed XFO header check behind reverse proxy (used by clients when embedding external websites). * Fixed rounding error in learning progress calculation. * Fixed `security.cors.origins` setting. * Fixed import of data from older versions. Security: * Fixed DoS vulnerability in authentication handling behind reverse proxy. Configuration changes: Minor changes to the web server and Tomcat proxy configuration are required (see [installation guide](src/site/markdown/installation.md)).