Sonarr adding unrequested series automatically

[NGOnline50]

Sonarr version (exact version): 2.0.0.5338
Mono version (if Sonarr is not running on Windows):5.20.1.34
OS: Synology via docker
Debug logs:
Description of issue:

Since a few weeks sonarr keeps adding new series to my library without me adding them.
I wake up in the morning with more than 10 new series, seemingly the same every day, in my library. One day, overnight sonarr downloaded over 400 GB of a new show which is completely uninteresting to me. I have to remove these series every day, but every few days they are readded again.

Where could this issue be originated? I tried shutting off all rss feeds, but as far as I know sonarr does not add series from some sort of list like radarr.

I hope we can come to a solution.

[Thirrian]

If your sonarr is exposed to the internet, I’d start by changing the username/password. Which you did configure, right?
There is no process in sonarr that adds series without you telling it to, or without granting access to other automation tools to do this on your behalf.

[NGOnline50]

Thank you for the idea. I tried to change the login, alter the api codes and turn off rss on indexers.
Today, however, it still added the series.
It almost seems like it adds a serie from every letter in the alphabet and some numbers 0-9.

Any other ideas?

[Thirrian]

Have you changed sonarr’s own api key (and restarted sonarr)? Settings - general.

[NGOnline50]

Thanks for the remark. I did alter sonarr’s api key, although I haven’t used it anywhere. I did not however force a restart of the application. I will do that now and check if it helped.

[NGOnline50]

After the force restart and updating api keys the series did not seem to come back. I’m unsure what specifically caused the problem, but it seems to have been solved. Thank you!