After the update to 27.0.0 synch throws an error:
“Error transferring https://my.site/remote.php/dav/files/my/path/ - server replied: Not found”
You did not fill out the support template. This:
… is only an information that your client cannot find a file. Without knowing the context, no one will be able to help you. So more insights please (log files, OS, Client, snap/AIO/Docker/Bare Metal etc) if you expect help.