The following has worked in the past for this issue:
Goto the URL opera://about, take note of the "install" path, and close Opera.
Hit Windows key + r to open a run dialog, type cmd and press enter.
Then, type the following and press enter to start Opera:
"C:\Program Files\Opera\launcher.exe" --show-component-extension-options
(Adjust path to your launcher.exe based in your install folder that you took note of earlier.)
Then, once Opera starts, wait 30 seconds. Then, goto the URL opera://extensions, turn on developer mode, and click "Update" at the top of the page.
Then, goto the URL opera://about and check for updates. If there's an update, let Opera update. If there's no update, don't worry.
Then, when all done, restart Opera.