This User Is Allowed A Maximum Of 18 Concurrent Shells, Which Has Been Exceeded Error In Exchange 2010

I came across this error message regarding the number of concurrent shells being exceeded while using EMC 2010.

Connecting to the remote server failed with the following error message. The WS-Management service cannot process the request. This user is allowed a maximum of 18 concurrent shells, which has been exceeded. Close existing shells or raise the quota for this user.

PS Error

The above error message is self explanatory. The user in question has more than 18 concurrent shell connections to the Exchange server, probably in a number of remote sessions to various servers.

The limit is imposed by the throttling policy in Exchange. In my case, the default policy has the maximum PowerShell concurrency set to 18.

Default throttling policy

How to fix this issue?

  • Close any unused/unwanted shell connections
  • Edit the throttling policy for the user and raise the limit to a higher value, say 25. Run Set-ThrottlingPolicy Default* –PowerShellMaxConcurrency 25 to set it. If you have a number of throttling policy, you need to find the one that is applied to that user and edit it.
  • You can also create a new policy with higher limits and apply it to the user (maybe for all admins).

12 thoughts on “This User Is Allowed A Maximum Of 18 Concurrent Shells, Which Has Been Exceeded Error In Exchange 2010”

  1. Hello Rajith, thanks for your post. I’ve come across the same issue recently and I found out that “rycycling” the MSExchangePowerShellAppPool Application Pool in IIS on CAS servers fixed the problem for the affected user. Before recycling I also tried to close any powershell.exe processes for that user user but did not find any. Hope that rycycling pool can also help others with the same problem…

  2. Hi ,

    We are running an automated application to create exchange mailboxes and for other exchange stuffs and we are getting same error which you have mentioned in above screenshot.

    As temp Solution we have increased PowerShell concurrency to 40

    I just wanted to know what / Which command I need run to Close any unused/unwanted shell connections.



    • Hi Sushant,

      Just close any powershell sessions that are running manually. You can write a small script for that if you want to scan a list of servers.


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