Could not establish trust relationship for the SSL/TLS secure channel

[PeterTran]

Hi,

I suddenly got this error:

An error occurred while sending the request.. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.. The remote certificate is invalid according to the validation procedure

I'm using Veeam Office 365 v3 CE for more than 3 months now, everything work fine until today. Trying to re-add organization but not successful:

Connect to Microsoft Graph: an error occured while sending the request.
The underlying connection was closed: could not establish trust relationship for the SSL/TLS secure channel. The remote certificate is invalid according to the validation procedure

Using same credentials on other Server works fine, so issue shouldn't be the credential itself. Using Application secret to connect, not Application certificate.

Appreciate any suggestion.

P/S: I tried to copy all configuration to another server, but unfortunately couldn't find that option (unlike Veeam backup and replication has Configuration Backup). How can I do that?

Thanks a lot.
Peter

[nielsengelen]

How did you add the organization? Are you using MFA with a certificate? Could it be that one expired? If not, I would suggest to contact support as it isn’t clear exactly what could cause this.

Moving to another server is explained in this KB.

[PeterTran]

Hi,

I did open case but haven't got anything for 2 weeks now, so I posted here.

I used Application ID, Application Secret, Username and App password to connect. No MFA.

Let me ask the support team again.

Regards,
Peter

[nielsengelen]

Can u let us know the support case ID once opened?

[Polina]

Peter,

If I get it right, your account is not enabled for MFA, and potentially you can use Basic authentication (simply username and regular password) to add the tenant to VBO. Have you tried this?
Next, as Niels suggested, if you stick to Modern auth, it'd make sense to ensure your App Secret key has not expired (typically, it's set for 1 year).

Thanks!

[THagen]

We had a similar issue a while back. We had no issues connecting/adding the organization, jsut the onedrive/sharepoing jobs that failed with that error message. Found that it was the firewall web filter that blocked sharepoint/onedrive.

[Mirza0724]

Hello,

Here is my case number: Case # 04975858

I am getting errors backing up O365 emails, teams, and one drive.

Code: Select all

10/20/2021 1:54:44 PM :: Processing mailbox ***** failed with error: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.. The remote certificate is invalid according to the validation procedure.

10/20/2021 1:54:44 PM :: Processing archive mailbox ******* failed with error: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.. The remote certificate is invalid according to the validation procedure.

10/20/2021 1:54:52 PM :: Failed to process team: IT Department. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.. The remote certificate is invalid according to the validation procedure.

Its been a month and support has not found a solution.
Was wondering if anyone had this error and how did you resolve it?

Thanks

[HannesK]

Hello,
at least one of the guys above could solve it by changing a firewall setting.

I did not read through all of the case... but classic question: when did it work for the last time and what changed before it started failing?

Best regards,
Hannes