Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed

Solution 1:

In our network I have found that restarting the Workstation service on the client computer is able to resolve this problem. This has worked in cases where a reboot of the client would also fix the problem. But restarting the service is much quicker & easier [and may work when a reboot does not].

My impression is that the local Windows PC is caching some old information and this seems to clear it out.

For information on restarting a service, see this question. It boils down to running the following commands on a command line:

C:\> net stop workstation /y
C:\> net start workstation

Note - the /y flag will force the service to stop even if this will interrupt existing connections. But otherwise it will prompt the user and wait. So this may be necessary for scripting.

Be aware that on Windows Server 2016 (+ possibly others) these commands may also stop the netlogon service. If so you will have to add: net start netlogon

Solution 2:

Even if you remove the shared folder via net use * /del, on the server side there is still a connection up there.

In order to get around this problem which Microsoft created by design you should map the drive in a way to let windows think it's another share on another server. The simplest way to do that is to use DNS aliases or ip addresses. In your case, if your first mapping uses the ip address like \\IP\Share with your current credential, you should use something like \\ServerName\Share password /user:Domain\Username this should create a new share with the new credentials.

Microsoft call this behavior by design .. i call it just stupid design.