Error: NSFDbOpen(<path to NSF>):This database is currently being used by someone else. (4269501)

When migrating with Notes Migrator for Exchange you receive the following error:

"Error: NSFDbOpen(<path to NSF>):This database is currently being used by someone else."

Notes Migrator accesses NSF files directly through the file system rather than connecting through the Domino server. This error indicates that someone (or another process) has the NSF file locked, so additional connections to it are not allowed.

To resolve this error you have three options. They are as follows:

1. Verify that the NSF file in question is not being used by others. Then go to the Domino Console and run the following command:
dbcache flush

This command will release any connections that the Domino server is holding to the NSF file.

2. Select "Through Domino Server(s)" on the "Specify How to find server mail files" screen

3. Make a local replica of the NSF file and migrate from the replica.