I always spin up a current version of the EX cu(#) server and migrate all the mailboxes to it instead of doing an in-place upgrade of the EX server. I just find it works better because upgrades have torched me in the past. 

I have all my mailboxes migrated over except PF's. 

Going from Build 995.29 to Build 1104.5. Separate virtual servers, with separate mailbox storage. I know that migrating the public folders in the past was difficult but this year it's been more.

I'm in the midst of migrating the storage from Mailbox1 to PFMailbox and the Branch.ps1 script wouldn't let me do the top level IPM_SUBTREE folder this time. So I'm manually doing all 165 folders (180gb) But there are some that are failing. I need to know what I need to look at to see what's going wrong. 

Well one thing it ended up being was that the Organizational config max size limit was tripping up on the migration because files exceeded the transport size limit (unlimited public Folder size limit) after that it was "too many large items" so I just exported all the contents to a PST, moved an empty folder, and imported the content back in. Viola - circumnavigation to the rescue!

• Marked as answer by Newmar Corporation 15 hours 26 minutes ago