Decryption suddenly failed for all Webpages using Sectigo Certs

Blyat_tschuli — Wed, 14 Jan 2026 09:16:54 GMT

Hi everyone,
Suddenly Websites which are using Sectigo Certs stopped working because the Certificate is not trusted anymore after decrypting. for example:

a.) https://client.mobilitybusiness.totalenergies.com/signIn
b.) https://login.teamviewer.com/LogOn/

Our Traffic log looks like this:

( cn contains 'teamview' ) and ( error eq 'Received fatal alert CertificateUnknown from client. CA Issuer URL: http://crt.sectigo.com/SectigoPublicServerAuthenticationCAOVR36.crt' )

I already Uploaded the whole Chain of the Issuer to the following Path on our WAN Firewall:
Device -> Certificate Management -> Certificates

But I am still getting this error:

Thats the first time I am facing this Problems
Any ideas?

Thanks in advance and have a nice week

Edit: I was sure i posted this in Discussions -> Network Security -> Next-Generation Firewall Discussions.

Somehow it ended in Discussions -> General Topics

Re: Decryption suddenly failed for all Webpages using Sectigo Certs

Blyat_tschuli — Wed, 14 Jan 2026 12:23:47 GMT

The Solution was to upload the Root and the Intermediate Cert like I already did.

But I just forgot the tick the "Trusted Root Ca Cert" checkbox on the Root CA Cert... after ticking and commiting it worked....

topic Re: Decryption suddenly failed for all Webpages using Sectigo Certs in General Topics

Decryption suddenly failed for all Webpages using Sectigo Certs

Re: Decryption suddenly failed for all Webpages using Sectigo Certs