The underlying connection was closed

​​​​​​The underlying connection was closed: This error message may occur when migrating a large item (containing large attachments, for instance). The Destination system will keep a connection open only for so long, after which the connection will be closed (timeout).


If the referenced server's configuration is under your control:

  • Increase the connection timeout for incoming data transfers (see the sample screen shot below for IIS; use a value larger than 120).
  • Increase the size limit of items that can be created through the API.

Once the mailbox migration completes:

To access the dialog below:

1. Go to the Exchange Server.

2. Start the IIS manager (run -> inetmgr.exe)

3. Browse to the default website or the Exchange website.

4. Find the website under which it is located.

5. Right-click on Manage Website -> select Advanced Settings -> expand Connection Limits.


Was this article helpful?
0 out of 4 found this helpful