Last week (4/14/2022) some users encountered this Google Calendar error:
[Google Calendar] Synchronizing folder ‘<your gmail account>/Tasks’ failed due to the following error: Sequence contains no elements
Google has recently updated its Calendar API and this error pops up when a Task folder (either the default or one manually created) is empty.
You can quickly fix this by adding a task into such folder or install this fix:
eM Client 8.2 for Windows: https://www.emclient.com/dist/v8.2.1706/setup.msi
eM Client 8.2 for macOS: https://www.emclient.com/dist/v8.2.1706_Mac/setup.pkg
eM Client 9.0 for Windows: https://www.emclient.com/dist/v9.0.1648/setup.msi
eM Client 9.0 for macOS: https://www.emclient.com/dist/v9.0.1648_Mac/setup.pkg
WARNING! If you are not experiencing this bug, please do not install these versions yet as they are simply meant to resolve this specific issue.
Updates with more fixes and improvements for eM Client 9 will be released soon as an official update.