If you receive an error attempting to download sessions from a server that says something about "The file exists" - the most common issue is that your local temp directory is full. You might see this in a messagebox, or in the MiForms logs.
The solution is to clear out your Temp folder - the local equivalent of C:\Users\[YOUR USERNAME]\AppData\Local\Temp. Simply navigate to that folder and delete the files, or use the Windows Disk Cleanup utility for your local storage disk.
There are many sources for the data in this folder, and too many files or too much data size can cause the directory to become "full".
If this is the solution, you will immediately return to normal usability.