Ways to transfer documents from one vault to another?

Replication can be used to move content between vaults. Content Replication and Archiving in the user guide has instructions for the set up and comprehensive documentation is available in Replication and Archiving - User's Guide.

I would like to point out a couple of things that you need to consider:

1. Make sure you have the same Aliases on structure elements in both vaults (Class, Properties, Value Lists, Workflows, Workflow States etc.). This ensures that the documents fall correctly in place in the receiving vault.
2. Time is a concern - particularly if one or both vaults are in M-Files Cloud. I recently moved around 15.000 files from a cloud vault to on premise via blob storage. Some of the files were large zip files (2-3 GB). I had to break up the replication in batches of not more than around 2500 documents in each batch, and exporting one such batch from the cloud vault could take 10 - 15 hours or more. In several occasions the transfer seemed to halt at around 50 - 60% of step 5 and I had to break it off after perhaps 20 hours. So it took almost a week to complete the transfer. In the end it worked out, but it certainly added some grey hair!

Thank you for the additional info! Will definitely have to check for Workflow aliases or probably just make a new one for this class and match it with the workflow in the older vault, as for the properties they are all the same (name and alias).

Oh wow okay, thanks for the warning. We don't use any cloud services and the largest files are around 150MB, so maybe it will be a bit faster for us? Hadn't had the time to check this out since our main guy is sick and at home, is the vault usable during the replication or do you have to bring it offline? Any other setbacks you encountered?

Both vaults are available during replication. No need to bring them offline. However, you may need to disable users in the old vault to prevent them from adding new content during or after the export. Alternatively, you can run a last export with filter setting "Last modified > dd-mm-yyyy" with a date matching your first export. When that has completed you could take the old vault off line to prevent any further activity in that vault.

If both vaults are on the same network and the server has adequate resources I would expect the transfer to go much faster than what I experienced.