Suddenly unable to back up MSSQL with this error 19:599.

hi @Veerasak

Please ensure service on client is up and running, there are no process crash on client for sqlbackup.exe (from Event veiwer--> applciation logs -- check for any faulting process )
Default Port 8400,8403 are open between commserver, client  and MA, av exclusion are inplace.
please review this kb article
https://kb.commvault.com/article/63604
 

look up for cvd.log , cvfwd.log , SQLbackup.log to check further more on the issue.

if still a problem support case may help for engineer to assist.

Thank you @Sujay kumar 

I am sure that both Commserve , MA and the Client are service running normally.

And I can telnet Commserve between client with port 8400, 8403 normally.

Did you make any changes? What version are you running? Is it an AG config? If so, can the nodes communicate between each other on Commvault TCP ports. Are you using network topologies?

Two possibilities

1. Communication
2. Legitimate process crash

#2 is easy to check - go check the windows application log for any crashes. on the client machine

#1 If not a crash, It sounds like communication towards client is good, but it is being blocked on reverse. Just checking 8400 and 8403 is not accurate to depict if communication is good. Commvault uses random high ports for communication unless you are using a network topology or configuration to restrict the ports are used. I would implement a network configuration here and limit connectivity bi-bidirectionally for 8403 and see if that helps. Of course you should check comms from the client to MA/CS on 8403 assuming that will be your network/firewall port (it is by default 8403).

Probably going into way too much detail here, but if you want to thoroughly test reverse communication without network topologies:

1. Access the registry of the CommServe, and head to:
   HKEY_LOCAL_MACHINE\SOFTWARE\CommVault Systems\Galaxy\Instance001\Runtime
2. The high ports for the services the CommServe is using is stored here, for example: JobManager_v4
3. The client should be able to telnet/cvping to the number (port) assigned to our example, JobManager_v4
   
   e.g JobManager is running on port 50148