System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) System.IO.Path.GetTempFileName()
This error looks like not Sitecore related, and related to your server configuration.
(Sitecore calls system method
System.IO.Path.GetTempFileName() with no params and receives the error)
Please check what is the
%TEMP% variable defined on your machine.
It may be that it looks for a location that does not exist or that the IIS AppPool user do not have read/write permissions for that folder.
You can check the
%TEMP% variable value using the following method inside the command prompt:
C:\Users\vlad>cd %TEMP% C:\Users\vlad\AppData\Local\Temp>
If that folder (result of request on your side) is existent – check if the AppPool user has the appropriate access rights.