SharePoint Online "Sorry, there was a problem uploading this file. Please try again."

Hi Dorje-McKinnon,

I have a similar issue. I have one team site sync'd via OneDrive for Business and another team site which we access via drag/drop or checkin/checkout/upload method (I'll call it the "non-sync'd" site). We started a large upload (197MB) on the non-sync'd site and it would fail with *any* activity (upload or download sync's) on my OneDrive for Business for the alternate team site with error "Sorry, there was a problem uploading this file. Please try again. [Retry]". 

I was able to recreate this several times on two different user accounts. My resolution was to not generate any file changes that would cause OneDrive for Business syncs and then hope that none of the other team members changed a file during the upload. It worked but we have a very small team so I was lucky.

Give it a try and see if you see something similar?

Cheers,

Trevor