Outlook reporting error message 0x80040600 in send and receive

I faced this issue yesterday and it was due to my PST file getting uploaded to OneDrive as the PST file was busy being uploaded it reported me this error.

So, the resolution would be this error occurs when there is an issue with your PST file or it not communicating or available properly to your outlook client. So, check your PST file or stop the one drive so that the task is freed up for the outlook to fetch your emails.

Please let me know if it worked for you in the below comments.