Unable to perform application-aware processing because connection to the guest could not be established

[koppesbouwkunde1]

Man, this error kept me busy for days. Read all about it and tried all solutions in vein. To keep it short: I had disabled NTLM. And that's a big nono: microsoft-hyper-v-f25/feature-request-k ... 50103.html.
After re-enabling NTLM, VBR ran fine again....

[Mildur]

Hi Simon

Yes, NTLM is required.
Kerberos only environments with disabled NTLM will be supported with V12.

Thanks
Fabian

[FalconDIgital]

2 things,
1 ) how come this can be disabled etc as you mentioned in the post though i am using Veaam 12.1
2 ) secondly if authentication is the issue then why Test is passed while configuring the AAGP.

[david.domask]

Hi Raja, welcome to the forums.

Can I ask you to elaborate on your questions a bit more? Is the situation that you have disabled NTLM and operations are working fine within Veeam? Just want to ensure I'm understanding correctly because as Fabian mentioned Veeam v12 introduced support for Kerberos only environment, but not sure that I got your question correctly.

For your second question, can you define AAGP please? It sounds like you're discussing the Test Now button in step 4 on the linked User Guide page, but if you could clarify we can better answer.

[FalconDIgital]

Thanks a lot David,
actually, AAGP is Application Aware Guest Processing and found this acronym in some kb article.
i have configured job with AAGP primarily for MS SQL DB, yes it was exactly step 4 and it was sucessfull in my case.
but when i run the job , initially it failed recovery check point failure , it was fixed by windows team at their Hyper-V manager settings , then again it has been consistently failing because of below error.

Processing ALWAYS-ON-1 10.15.15.41 Error: Unable to perform application-aware processing because connection to the guest could not be established
Failed to create VM recovery checkpoint (mode: Veeam application-aware processing) Details: Unable to perform application-aware processing because connection to the guest could not be established
Error: Unable to perform application-aware processing because connection to the guest could not be established
Processing finished with errors at 8/22/2024 5:26:24 PM

I am using Veeam 12.1 build, now

1 ) how should i fix this error, can i enable NTLM on Veeam side if needed ?
2 ) is recoevery checkoint is mandatory for AAGP based backup.
3 ) credentials enetred required at each job execution or they need only once on guest side ? in case organization policy is to change password routinely.

[david.domask]

Hi Raja,

Thank you for the clarifications.

The error itself is not expected, and we will need you to open a Support Case and allow Veeam Support to review the job. The message is a bit mixed so it's best that Support review the logs more deeply to understand why the recovery checkpoint creation is failing and why a connection to the GuestOS being backed up does not seem to be possible at the moment.

Be sure to include logs from one of the affected jobs for Support to review.

For your questions:

1. I'm not confident it's about NTLM at first blush, but if you're in a position to test it, it would not hurt, but still it's best to let Veeam Support review the debug logs.
2. Yes, it's required.
3. If you are rotating passwords in the environment and _not_ using Group Managed Service Accounts, you will need to update the passwords within Veeam when the passwords are rotated, correct.