Upgrading from 3.4 to 3.5.31

Hi,

After upgrading Contao from version 3.4 to 3.5.31, I have a problem. Everything was working fine, but when I went into File Manager and pressed "Synchronize", the pages and backend are not loaded, I get the white background with the spinning loading page indicator in Chrome. What can be the cause of this?

Thanks

How did you perform the update?

Are there any error messages in system/logs/error.log?

Problem is solved, it just needed a few hours to finish for some reason :) But now it's ok.