Sharepoint Online Migration Manager failed tasks

Copper Contributor



I have a list of target sharepoint online sites in the same tenant in the format which are utilizing their Documents library for hosting files I need to migrate from on-premise Windows Server 2019 File server SMB shares (source paths are UNC paths). I have 10 source/target locations and have tried to run the migration using a csv file (batch migration) as well as migrate the sites one by one. When running the csv batch all migration tasks fail and when I click on the failed task and click "Download task report" nothing happens, so I cannot see any logs.


Afterwards I tried to run each migration one by one and in this case the first three migration tasks succeeded but all remaining migration tasks failed, again without being able to download the task report for any of them. Rerunning the failed tasks at random times continues to fail. I have double checked permissions and configuration of the migration manager agent on the source file server (both file server SMB/NTFS permissions and target Sharepoint Online permissions (site collection administrator and site owner).


Do you have any ideas on how to troubleshoot this further?

2 Replies
How many files do each of the failing task should migrate? I have found that Migration Manager is not able to deal when the number of items to be migrated is higher than 100.0000

@Juan Carlos González Martín 




The migrated files are definitely below this limit. I have also carried out the migration to another M365 tenant and it worked without issues.