Error on click for Update to 1.2.2

[morphinestyle]

This update to 1.2.2 didn't work as usual, it returns this error:

Incomplete installation
It looks like you are trying to use Akeeba Panopticon from the Git repository, however you have not completed all build steps.
Please refer to the README.md file on the project's repository for building Akeeba Panopticon for use.

How can I solve it?
Do I unzip version 1.2.2 again and overwrite the old installation?

[nikosdion]

The message means that the vendor folder is missing or incomplete.

Retry extracting the update ZIP file.

If this doesn't work, ask your host to reset the PHP OPcache. Ideally, you should have OPcache expire at 2 to 5 seconds, and make sure that opcache_invalidate is not disabled on your server.

[morphinestyle]

Same as here again: #754

[nikosdion]

Fabio, this is a misconfiguration of your server. If you don't fix it, it will keep happening. I already told you what to do.

you should have OPcache expire at 2 to 5 seconds

If you still don't get it, here's what you need to configure at the very least in PHP:

opcache.validate_timestamps=1
opcache.revalidate_freq=2

Please do read the fine manual.

[morphinestyle]

Strange situation, I'll try to understand more. Thank you!