When migrating users using the Microsoft Online Migration tools, if the total number of errors exceeds 5, the migration for that user will stop and an error like the following will be logged:
The WebDAV injector has stopped migrating mail items for user SMTP:firstname.lastname@example.org because the number of failures has exceeded the failure tolerance of 5. The injector will ignore any remaining items for this user’s mailbox during this migration session.
Here are some recommendations on what to do.
1. Try and remigrate the mailbox. Depending on the errors, it might work the second time. Typically remigrating should not create duplicates and should run must faster since it doesn’t have to remigrate what has already been migrated. Errors that lend themselves to working the second time are errors that appear to be network related, such as:
Rerunning the migration and reducing the thread count can also help with these types of errors. Errors that typically don’t fix themselves are those that reference are particular object:
2. If the remigration fails and you are getting errors about individual items failing try moving the mailbox to another to another store on the source server and then remigrate the account. The mailbox move will sometimes clear up mailbox corruption.
3. If it still doesn’t work, export the mailbox to PST and import the PST. This way always works, but the problem is the messages aren’t replyable in Microsoft Online.
If you don’t want to export the mailbox to a PST and reimport there is another option, it’s just time consuming. Using the migration PowerShell commands it is possible to get details on the messages that are failing.
You can download this script which will help you identify the messages. There are a few things you’ll have to modify in the script before running it. When running it you’ll need to provide the email address of user that is failing, and then the UID of the message that is faing. The UID can be found in the error logs and will look similar to:
The item with SourceUID value ARgAAAAYbzngAAAAAAAAAAAAAAAA
The script will output additional details about the message. You can then go into the mailbox and export or delete it. Do this for all 5 messages that are failing and then try the migration again and hope you don’t get 5 more failures!
If you need assistance with the script, email email@example.com. If you have other suggestions, please post them in the comments section below!