Hello! I use this feature everyday, and I really need help!

It begins after last maintenance. After pressing G button on iPad I receive message box with error:
"Sync with google calendar failed (502)".
And it is really failed.

But synchronization is working in web.
Please help!

Screen https://www.dropbox.com/s/42hvmby2nd7tey4/%D0%A4%D0%BE%D1%82%D0%BE%2020.12.13%2C%208%2027%2049.png