I Have checked the network , its working fine and it is the same. Did not understand
why out of the blue moon this issue has arose!
This error is happening when NAV tries to copy a file it cannot gain access to.
When NAV uses this command, to access a file, then it does it in the context of the NAV service user account, not the end user from their client. And any network paths or drive letters are as seen from the server.
So you should try to test the same process both from other clients (test with login as administrator) and if possible, try to run it from the Windows client directly on the NAV server. If it works from here, then your have your problem.
If you search the internet for your main error "A call to System.IO.Copy field with this message: The specified network name is no longer available." then it will show you that a lot of people have reported that this error has been related to their firewall. So you should try to test it with the firewall turned off.
We use NAV just from our windows client, and I login as admin and other users log in as limited users access, still
the message has been appearing.
As for the firewall . Our Users are in the same LAN , one office premise the users who reported this error, are in the same LAN connection.My IT Support has given a green signal from their side, as there is not network issue.
As both Erik P. Ernstand @RockWithNav says, it is a folder access issue. The problem usually happens because when NAV was installed the SETUP.EXE file was not executed as Run As Administrator. Try changing the folderpermission for the folder:C:\ProgramData\Microsoft\Microsoft Dynamics NAV\110\Server\MicrosoftDynamicsNavServer$DynamicsNAV110\temp- But again, it would still be nice to know. What Version of NAV? Build Nol? Standard-code or not?