I can not log on to the local server after updating the new version 2.5 Linux desktop clients
You already attached the right tag with missing information, here is the documentation where and how to get more information:
https://docs.nextcloud.com/desktop/2.3/troubleshooting.html
The problem gets if you use only the local server as an example https://192.168.1.2/nextcloud
but If you use a domain there is no problem