Major changes in 2.0

• Database backend switched from LevelDB to SQLite. There is a migration on first launch which can be lengthy for larger setups. The new database is easier to understand and maintain and, hopefully, less buggy.

• The logging format has changed to use structured log entries (a message plus several key-value pairs). Additionally, we can now control the log level per package, and a new log level WARNING has been inserted between INFO and ERROR (which was previously known as WARNING...). The INFO level has become more verbose, indicating the sync actions taken by Syncthing. A new command line flag --log-level sets the default log level for all packages, and the STTRACE environment variable and GUI has been updated to set log levels per package. The --verbose and --logflags command line options have been removed and will be ignored if given.

• Deleted items are no longer kept forever in the database, instead they are forgotten after fifteen months. If your use case require deletes to take effect after more than a fifteen month delay, set the --db-delete-retention-interval command line option or corresponding environment variable to zero, or a longer time interval of your choosing.