this period of time customer mail system upgrade, basically the same as before, CAS+HUB NLB, DAG database,

try creating a new mailbox. Error reporting

Load balancing failed to find a valid mailbox database.”

but if you choose a specific database it’s ok,

after the search reasons are as follows:

1) select update RU6

for exchange sp1

2) check to see if the database has dismount

3) mail database server not installed, but I think this should appear this error 🙂

reproduced in: https://blog.51cto.com/4763146/987147