Forum Discussion
SharePoint Online Calendar View Error
Having used ShareGate many times I don't think anyone is going to be able to give you a specific answer to why this failed without seeing it. Did ShareGate give you any warnings or errors? Having the extra columns or overlays may be the issue. If you want to get to the bottom of it then create a new on-prem calendar and add the same features and migrate it until it breaks again. Probably a rabbit hole you don't want to go down.
My suggestion would be to create the new calendar list with the same name and migrate the content in rather than migrate the list. Recreate anything you need to and you can complete the "migration".
Andrew Hodges thanks for the response. I haven't been able to ID what happened exactly yet, but I ended up exporting the data into an excel spreadsheet and creating a new calendar with the same column names. Then I used quick edit to copy the data from the spreadsheet into the new calendar. Now the new calendar works as it should. I'll try to figure out what's going on with the old one.