This is very strange.
We have a merge publication with a lot of subscribers. One of them suddenly failed to synchronise with the message "The subscription to publication '(publication name)' is invalid or has not been set up correctly."
Investigating, I found that the
subscriber_db value on the publisher has suddenly become blank, if I use
sp_helpmergesubscription. The value was definitely there a few days ago, when the subscriber last synchronised successfully.
All other subscribers are unaffected.
How can I investigate how this happened? Is it possible to correct it without re-adding the subscription?
(This happened once some time ago and, without a value to
subscriber_db, the subscription could not even be dropped. A new one had to be created alongside the "faulty" one.)