hedgedoc/docs/content/guides/migration-troubleshooting.md
David Mehren b47f1e80b4
Add docs about troubleshooting migrations
Signed-off-by: David Mehren <git@herrmehren.de>
2021-03-03 12:38:44 +01:00

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# 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:
```sql
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.