A Guide To Fixed Exchange Server Error 9646

Exchange server is one of the widely deployed mail servers of the present arena. Its portfolio of features such as connection filtering, social collaboration and intelligent message filter act as a feather in the cap. But certain hindrances even in the most flawless applications may affect your business workflow. In context to Exchange Server, the hurdles which are usually experienced are the errors in the server. In this piece of writing, we have focused our considerations on Exchange Server error 9646.

Scenarios When Exchange Server Error 9646 Is Experienced

In the event of the below-mentioned scenarios, the Exchange server gets disconnected from the service account and ultimately leads to the occurrence of Exchange server Error ID 9646

There are three probable scenarios that result in the occurrence of Exchange Server Error 9646:

  1. Microsoft Exchange Server has been installed into your machine. Additionally, a service account to facilitate interaction between Exchange Server and a third-party application has also been created. The service account has accessed more than the default permissible MAPI sessions in order to synchronize mails. The default number of connections that an account can open is 32.
  2. Another reason which marks the occurrence of this error is the server that is running the Exchange server is currently a part of the forest resource. In this, a service account is created so as to interact with the Exchange server and the MAPI sessions are quite high.

The Exchange Server follows a certain policy regarding the consumption of server-side resources. This policy ensures that the server-side resources consumption is limited to a certain parameter so as to prevent a single user from exhausting the entire resource quota. If any of the above-mentioned symptoms are shown by the server it straightaway implies that either a single user has exceeded the limit by opening too many objects or has left too many objects in an open state on the server.

Methods to Fixed Exchange Server Error 9646

  1. There are different methods by the help of which the users can work around the Exchange Error 9646. To fight back symptom no.1, the service accounts should be granted the ‘View Information Store Status’permissions. The ‘View Information Store Status’ permission enables the Exchange user to access an unlimited amount of connections. Follow the given mentioned steps to do the same:
  • Open the Exchange System Manager.
  • Select the desired Exchange Server mailbox store.
  • Right-click on the Exchange server mailbox store to open Properties.
  • Select the Security Tab.
  • Select accounts for which you have to set permissions.
  • To list the account, go to Add option and then click the account name and then add.
  • Browse to the Allow Column option.
  • In this check, the option Select The View Information Store Status.
  • Uncheck all the permissions that are not necessary and then click Ok.

Note: This method is not applicable to Exchange Server 2013. In this version, we need to make changes in the “Administer Information Store”.

  1. Another method to nullify this error is by making the desired changes in the Registry Editor to change the maximum number of MAPI sessions. This can be done by following the below-mentioned steps:
    • Open the Registry Editor.
    • Browse to the following location:


  • Click this key.
  • If the Maximum Allowed Sessions Per User Entry is not mentioned then edit the key.
  • Click on the Edit option.
  • Select the New option and click on DWORD value.
  • In the entry name option, write Maximum Allowed Sessions Per User and press Enter.
  • Right-click on the Maximum Allowed Sessions Per User entry.
  • Select Modify.
  • Select the Decimal option.
  • In this specify the desired value of the number of IMAP sessions.
  • Click Ok.
  • Exit Registry Editor.
  • In the Run option, type services.msc.
  • Click Ok.
  • Select ‘MS Exchange Information Store service’.
  • Select the Restart option.

Most of the time these methods work. But when these methods fail, then there is a chance of corruption in EDB files. So, to remove corruption from EDB files you can use EDB to PST Converter. It is the best way to recover corrupted Exchange EDB files.


In this blog, I have explained methods to fix Exchange Server Error 9646. Along with scenarios and reasons in which this error occurred. I hope your issue got solved. If not then you can use EDB to PST converter prescribed above. It is the tool to recover Exchange EDB files.

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