Msg 3743 says the database is enabled for database mirroring, and mirroring must be removed before you drop it. Here is how my client got past it.
Mirrored Database: Move Files Without Breaking Mirroring
To move the files of a mirrored database, change the file paths on the principal with ALTER DATABASE, stop both instances, move the files, and start them again in the right order. This post tests the T-SQL steps on a demo database and describes the mirroring steps from the documented behavior. It also covers what to check afterward.
SQL SERVER – AlwaysOn Join Error – Msg 1408, Level 16 – The Remote Copy of Database “SQLAUTH” is Not Recovered Far Enough to Enable Database Mirroring or to Join it to the Availability Group
I do provide consultancy services for deployments, including AlwaysOn availability group deployments. AlwaysOn Join Error.
SQL SERVER – Database Mirroring Login Attempt Failed With Error: ‘Connection Handshake Failed. There is No Compatible Encryption Algorithm. State 22
Moving from database mirroring to an AlwaysOn AG failed with a handshake error: no compatible encryption algorithm. Comparing the endpoints showed why.
SQL SERVER – Mirroring Error: Connection handshake failed. Could not send a handshake message because the connection was closed by peer. State 26
A mirroring error, connection handshake failed, State 26. The checks I once asked readers for, run on SQL Server 2025 on a real endpoint.
SQL SERVER – FIX : Msg 35295, Level 16 – Log Backup For Database ‘DBName’ on a Secondary Replica Failed
During load testing, a log backup on a secondary replica failed with Msg 35295 because the last backup LSN was ahead of the redo LSN. Here is why.
New AD Domain: Moving an AlwaysOn Availability Group Node by Node
After an acquisition, my client had to move an AlwaysOn availability group to a new AD domain. These are the 12 steps I shared, moving one node at a time from DomainOld to DomainNew.