Originally posted by Caerpre:

Absolutely loving GSM. The whole package really helps me take control over my server management.
I'm having one issue however and I can't figure out how to resolve it. Currently everything about running the server works perfectly and I've set it to do automatic updates using SteamCMD. This also works as intended as best I can tell. However when an automatic update occurs the server does not restart as it's meant to. It shuts down the server, connects to SteamCMD, updates the server, closes SteamCMD, and then just hangs...
GSM says "Performing Maintenance" and "Waiting for Update to Finish" but it never proceeds beyond that point. I have to close GSM, reopen it and then start up the server. Which sort of defeats part of the point of automatic updates since I'm still manually restarting the server every time.

Am I doing something wrong?

I was having the same issue but eventually figured out how to fix it.
First some information from the Valheim Dedicated Server Manual PDF that is included in the dedicated server folder:

Originally posted by Valheim Dedicated Server Manual:

When you wish to stop running the server, ​it is important that you close it by pressing CTRL+C in the Command-window​. If you close it by clicking the X in the window frame the Server may keep running in the background, we don’t really know!

Now with that information in mind, make sure you do not have any instances of the CMD window running by right-clicking the Windows taskbar and shut down any instances of CMD that is running. (I had two instances running that I forced closed.)

Now, to fix this in GSM head to Program Settings and navigate to Server Shutdown. Tick the box that says Send keys to shutdown the server: and inside the box you type in ctrl+c

Save & Close and you are done.
Click the Perform Maintenance button and GSM should look for updates, apply, restart and all that without hanging.

I hope this solves your issue as well!