If you go to the Brent Ozar blog, on the right-hand side you can sign up for a 6-month DBA training plan, which I think is a weekly email (or...

... is what a sadist would write.

Do do as SQLRNNR suggests and look into patching to 2012 SP3 CU7 if you haven't already. The patch was only released in January this year.

Are there any other databases in the AG? If not you should be able to remove the replica and add it back in again without having to take the database...

The situation may have resolved itself now, but when I had something similar I think I was able to restore over the database (then drop it)- is that an option...

I haven't had this problem myself yet, but I was aware that it could be an issue because as a result of parallelising the log transfer process, the redo process...

No, not with mirroring. You could use replication or log-shipping, or (if you upgrade) AlwaysOn Availability Groups.

When it works, it's brilliant.

Isn't the pull subscription attempting to run from a SQL Express instance?

https://technet.microsoft.com/en-us/library/ms165686(v=sql.105).aspx 

SQL Server Express does not include the SQL Server Agent, which is typically used...

I didn't know that specifically but I assumed it, so I'm pleased to find out I was right.

Thanks for the list. 3226 is essential for me. I can't stand wading through a list of successful backups when I'm trying to find something in the error log. I

I'm just going to run away now.