gitea: Permission denied after latest docker upgrade

• Gitea version (or commit ref): 31aa00f
• Git version: 2.11.0
• Operating system: Debian
• Database (use [x]):
  • MySQL
• Can you reproduce the bug at https://try.gitea.io:
  • Not relevant
• Log gist:

gitea     | Found app.ini config file, migrating database
gitea     | migrate: /data/gitea/conf/app.ini: Permission denied
gitea     | Jan 10 15:41:14 syslogd started: BusyBox v1.28.4
gitea     | Jan 10 15:41:14 sshd[22]: Server listening on :: port 22.
gitea     | Jan 10 15:41:14 sshd[22]: Server listening on 0.0.0.0 port 22.
gitea     | 2019/01/10 15:41:14 [T] AppPath: /app/gitea/gitea
gitea     | 2019/01/10 15:41:14 [T] AppWorkPath: /app/gitea
gitea     | 2019/01/10 15:41:14 [T] Custom path: /data/gitea
gitea     | 2019/01/10 15:41:14 [T] Log path: /data/gitea/log
db_1_260cddf62aee | 2019-01-10T15:41:14.327150Z 2 [Note] Aborted connection 2 to db: 'gitea' user: 'gitea' host: '192.168.144.3' (Got an error reading communication packets)

Description

After upgrading my docker-compose instance from Gitea to the latest version I get the following error (as seen above).
I already tried chowning the my mounted gitea volume to 999 (docker) and 1000 (default Gitea user) with now success.