Error
The underlying connection was closed.
Cause
This error message may occur when migrating a large item (containing large attachments, for instance). The Destination system will only keep a connection open for so long before closing it (timeout).
Resolution
If the referenced server's configuration is under your control:
- Increase the connection timeout for incoming data transfers (see the sample screenshot 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 is completed:
To access the dialog below follow the next steps.
- Go to the Exchange Server.
- Start the IIS manager (run -> inetmgr.exe)
- Browse to the default website or the Exchange website.
- Find the website under which it is located.
- Right-click Manage Website.
- Select Advanced Settings.
- Expand Connection Limits.