A Microsoft file hosting and synchronization service.
Hi A.T.O,
I would like to confirm how you migrate the files from Dropbox to OneDrive.
If you copy and paste the files directly to OneDrive, please check the limitation of OneDrive:
You can also check the suggestions in this article: Maximize upload and download speed
For the sync limitations, please check this article:
Invalid file names and file types in OneDrive, OneDrive for Business, and SharePoint
Do you have OneDrive sync client and Dropbox local application? They should have a local folder, it is more recommended to do the migration in the local folder.
And I suggest you upload the files to OneDrive in batches since it seems that you have a lot of data.
In addition, since you are using Insider version of OneDrive, please try using Production version if the suggestions above all don't work:
Best Regards,
Gloria