There is a hard limit on how long your AlwaysOn listener name can be. That is expected, what may not be expected is that the limit is mere 15 characters or less.
Yes even though the maximum length allowed for an AlwaysOn listener DNS name is 63 characters, in practice you can only specify up to 15 characters. This limit comes from the NetBIOS computer name restriction, which is 15 characters, even in the latest versions of Windows 2025. Technically, the maximum length for a NetBIOS name is 16 characters, but the 16th character is reserved for identifying the network device functionality, effectively limiting it to 15 characters.
The limit is for the name part, not the entire Fully Qualified Domain Name (FQDN), which can be up to 255 characters long.
So if you are using SSMS to create an AlwaysOn Listener, it won't even let you type in more than 15 characters:
If you bypass the GUI as I did back then and resort to TSQL, you will receive error similar to this:
Msg 41066, Level
16, State 0, Line 3
Windows Server Failover Clustering (WSFC) resource (ID
'70ce3804-e3ed-4db6-ad42-6936daeeb5aa') online (Error code 5942).
may not be running or may not be accessible in its current state, or the WSFC
resource may not be in a state that could
request. For information about this
error code, see "System Error Codes" in the Windows Development
documentation.
Msg 19476, Level
16, State 4, Line 3
The attempt to
create the network name and IP address for the listener failed.
may not be running or may be inaccessible in its current state, or
provided for the network name and IP address may be incorrect. Check the state
of the WSFC cluster and
network name and IP address with the network administrator.
On the surface, this will work and complete successfully:
In reality, the newly added Client Access Point will not come online, and your AlwaysOn resource will show as partially failed
Is there a solution or workaround that works?
Sadly, no. Though justifiably annoying, in the Microsoft Windows world, there is no way to get around this limit.
A potential alternative could be to install your SQL Servers in the Linux world without Windows Failover Clustering and Active Directory. I am told you could have a longer name for the AlwaysOn Listener in this environment. However, I have not tested this myself and therefore would not count it as a definitive solution. Even if it works, isn't that too much effort just to name your listener with more than 15 characters?
I ended up making a slight change in my naming convention so that the listener name would not exceed 15 characters.
Resources: