If it helps anyone else who isn't sure how to proceed, this is one way that worked.
It starts when you get the error "SQL Server version Your-Server\VEEAM is not supported: SQL Server 2008 (10.0.0.1600.22) or later is required"
* Make an encrypted backup from the Veeam menu that includes creds for jobs.
(my jobs have various credentials, I'd say that's normal for most of us.)
- use top-left-hamburger -> configuration backup -> select the encrypted option.
highest sqlexpress that can run on 2008R2 is SQL-EXPRESS-2014, download and extract it.
theoretically it'll run and upgrade existing instances, but whines and exits so no.
uninstall sqlexpress 2005 ( 1 item, Veeam's database)
uninstall sql2008 (many items including VIM databases from 5.0, 5.5, and 6.0)
no more sql applications
no more sql instances.
uninstall VMware client - (I'll put it back later though)
.. Now install sql-express-2014
the name it asked for is the instance name so call it VEEAM
.. this creates an empty database with the same instance name that B&R is going to look for.
.. Fire up Veeam (inc starting stopped services) and use top-left-hamburger -> configuration backup -> restore
.. I chose 'restore because I migrated' however when that was nearly done the Veeam installer slapped me on the wrist and did the 'recover failed server' parts as well.
Everything is fine, all my jobs etc. are still there and Veeam B&R is now running on an sql-express-14 database.
- caveat.. all my normal jobs are disabled, so I enable them again.
- It's currently rereading every tape in the library, perhaps I could have taken most of them out first but there's not that many.
- wait for the tape reading operation to finish.
- enable relevant jobs
test a manually kicked off job ==ok
let a scheduled job run and ensure it kicks off ==ok
browse VSphere from Veeam to ensure certs/perms are good == ok.
write a tape == ok
- wait for clear time with no backup tasks.
- make a new spare Veeam database backup (because tonight's backups will change the real data)
- upgrade to 9.5
.... went straight through with no issues.
so.. hope it helps...