https://github.com/duplicati/duplicati/issues/2530
^I could not find any lingers update folders to delete as referenced in this issue, but I doubt there would be any lingering versions considering this is my first update attempt
(New to Duplicati, so apologies for any novice mistakes)
I can't seem to activate the new version of Duplicati from 2.0.2.19 to 2.0.2.20. Following a check for updates, I am presented with text inviting me to activate the new version as it has been installed (see screenshot). However, nothing happens upon clicking "activate now." Multiple clicks in quick succession result in a popup saying "Activate failed: Missing XSRF Token."
For reference, I am running Duplicati as a service to avoid launching tray icons and eating up 8XXX ports for each user when accessing the GUI.

Sadly, there didn't appear to be any output in the "Show log" tab. Happy to look for logs elsewhere.
After restarting the service, the activation appears to go through.
Would be cool if the service automatically restarted to allow for activation, or if the client prompted the user to restart the service
I had the same problem today, I was trying to update from v2.0.4.23-2.0.4.23_beta_2019-07-14 to v2.0.5.0-2.0.5.0_experimental_2020-01-03 and was getting the same error.
Activate failed: Missing XSRF Token.
Restarting the duplicati service in services.msc did the trick.
Thank you @thomasyi17
Most helpful comment
Would be cool if the service automatically restarted to allow for activation, or if the client prompted the user to restart the service