In updating to the latest Kirby I ran into an issue when accessing the dashboard all I got was the warning below.
The widget does not exist at the specified path: /var/www/vhosts/socu.org/httpdocs/panel/app/widgets/._account
What happened was that OSX created ._ invisible files that transferred over when I FTP’d panel and kirby files. Kirby doesn’t like having any of those files in app/widgets folder. When I removed them Kirby worked again.
From which version did you upgrade?
It was from version 2.2.3
Thank you, I will look into this.
I have this happen when I transfer files from MacOS to a Samba share with a different file system. MacOS creates dot files to keep extra meta data or something that it can’t keep on a file system other than HFS+. In this situation the Samba share is on a Ext4 partition.
However the files got there, they shouldn’t cause this issue. 
It looks like I did not have those files in my version 2.2.3 widget folder, so the issue may extend beyond 2.3.1.
This issue has been fixed in Kirby 2.3.2.