An existing connection was forcibly closed by the remote host
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).
Mailbox Migration Resolution
If the destination server's configuration is under your control:
- Increase the connection timeout for incoming data transfers.
- Increase the size limit of items that can be created through the API.
Once the migration is completed follow the steps below.
Cannot Retrieve Permissions
Error message
The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.: /personal/leandie_cpgp_co_za/Documents/3D DRAWINGS/Item 4.2 (X-Tech)/M060642063 - 2010-06-02 Rev 1/Smalls Parts/Dwg/p10 - STANDARD.DWG ---> The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. ---> Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> An existing connection was forcibly closed by the remote host.
Cause
This generally happens in document migrations, specifically Office 365 migrations. This is almost always due to Microsoft throttling.