Symptoms
When running an Insane mode migration to Microsoft 365, you get one of these error messages on one or several of your items:
This item was not copied due to a fatal error on item '{0}' at the source. Fix the error or skip the item to complete the copy.
This item was not copied due to a fatal error on an item at the source. Fix the error or skip the item to complete the copy.
This item was not copied due to a fatal error on an other item. Check for items with error in this report.
Error Code
AZ-034-213
AZ-048-368
Details
Understanding how Insane mode works with a Microsoft 365 destination is essential for identifying the cause of a fatal error in ShareGate Migrate.
In Insane mode, ShareGate Migrate uses Microsoft’s migration API to offload the data transfer process. Here’s how it works:
Your content is packaged:
ShareGate Migrate bundles your source content into packages.
Each package contains multiple files, depending on their size and other factors.
A manifest package is created to include metadata and other configuration data.
Packages are uploaded to temporary Azure storage in your Microsoft 365 tenant.
Microsoft 365 imports the content from Azure:
Microsoft imports the data from Azure storage into your SharePoint Online destination.
This import process is handled entirely by Microsoft’s servers.
What causes a fatal error
Fatal errors occur during import when Microsoft 365 transfers your content from Azure storage into SharePoint.
You might encounter a fatal error if:
Over 100 files in a package fail to import with other errors.
Often repeating errors that pertain to a list's unique permissions limit or errors on many versions.
One or more corrupt files prevent Microsoft from completing the import.
When this happens:
Microsoft 365 stops the entire import of that package.
You’ll see a fatal error message in your migration report for every remaining file in the affected package.
Troubleshooting
To find the root cause of the fatal error, inspect your migration report for repeating errors in the affected list or library.
To inspect the migration report, you can export it as an XLSX and leverage Excel's filtering options.
In Excel, you can find which list or library is affected by a fatal error and filter the report to find other errors on that list or library that could have caused it.
Tip: See Tips and tricks to review your migration report in Excel to learn how to filter your report effectively.
If you find errors that caused the fatal error, look for the Help links column in the report. It should direct you to articles that can help you solve them.
Repeating errors can often be resolved by adjusting your Copy options, mappings, or the source or destination.
There is one particular error worth looking for, especially if you are migrating from a file share:
Unique permissions limit exceeded
SharePoint Online lists and libraries have a limit of 50,000 items with unique permissions. When you reach that limit, any subsequent item returns an error, which can quickly reach 100 and cause a fatal error for the package being imported.
This is the most common cause of fatal errors. It mostly happens when migrating from a file share when the app applies unique permissions to every item to reproduce the source's permissions.
It can also happen when migrating to a SharePoint Online list near its unique permissions limit.
If you find repeating errors about unique or custom permissions, you can:
Import your items without their custom permissions by turning off Custom Permissions in your copy options if you do not need to preserve these permissions.
Import your content to multiple libraries to reduce the total number of unique permissions.
Tip: Before you import your documents without their unique permissions, you can create new permissions for your destination library or create a few folders with custom permissions that your documents will inherit to manage who can access them.
Other causes
If you cannot find other errors and repeating errors that could cause the fatal error in your migration report, you might have a corrupted file, or the fatal error makes it hard to find what is causing it.
In these cases, you can use Normal mode as a troubleshooting tool since that mode copies your content directly into the SharePoint destination, bypassing the transition to Azure storage and avoiding fatal errors.
Try copying the affected list or content in Normal mode and look at the migration report for issues with your content. If you find a file that does not copy over because it's corrupted, you can try removing it from your source or skipping it during the migration in Insane mode afterward.
Note: We do not recommend extensively using Normal mode for migrations to Microsoft 365 to avoid throttling and other potential performance issues.