hedgedoc/docs/content/guides/migration-troubleshooting.md

Troubleshooting Migrations

In some cases, HedgeDoc might apply migrations without correctly saving the progress. In these cases, HedgeDoc will refuse to start with “already exists”-errors like ERROR: type "enum_Notes_permission" already exists.

To fix these issues, manual intervention in the database is required:

1. Make sure you have a way to edit the database directly. For SQLite, PostgreSQL and MariaDB/MySQL, you can use the respective command-line tools sqlite3, psql and mysql.
2. Get the name of the failing migration and append .js to it. For example, if you encounter this error

   == 20180306150303-fix-enum: migrating =======
   
   ERROR: type "enum_Notes_permission" already exists
   

   the name of the failed migration would be 20180306150303-fix-enum.js.
3. Make sure HedgeDoc does not run and insert the name into the SequelizeMeta table.
   Ensure your database shell is connected to the HedgeDoc database. The SQL-statement may look like this:

   INSERT INTO "SequelizeMeta" (name) VALUES ('20180306150303-fix-enum.js');
   

4. Start HedgeDoc again and observe if it starts correctly. It may be necessary to repeat this process and insert multiple migrations into the SequelizeMeta table.