Err_cert_authority_invalid

[gulshankumar]

Dear Community,

I'm facing an issue with my website's SSL certificate, resulting in an ERR_CERT_AUTHORITY_INVALID error.

I understand screenshots might not be the most effective way to convey the problem, so I've included the link to the SSL Labs analysis for my website: SSL Labs Analysis.

Given that our sites are likely to receive traffic from older devices, it is critical for us to address this issue.

Any assistance or guidance on resolving this matter would be greatly appreciated.

Thank you all for your support

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Current Settings

[rg305]

Please show us what is shown when you click "certificate information".

[rg305]

It's possible that your phone doesn't have the third cert in the local trust store:

The server is only sending the first two [that is expected].
What is the OS version running on the phone?

[gulshankumar]

OS Android 5 point something

Please have a look

[Osiris]

Please see Shortening the Let's Encrypt Chain of Trust

Android 5 is missing the ISRG Root X1 certificate.

Also, Android 5 is probably extremely vulnerable due to missing security updates.

[rg305]

That's the same picture.
Please click where it says "certificate information" in that picture and show us that information.

[Bruce5051]

@gulshankumar

OS Android 5 point something

@gulshankumar If you can upgrade to a much newer Android versions would be choice #1
if not here is a list of other Free ACME Certificate Authorities to consider using instead of Let’s Encrypt;
most have Trusted Anchor Root Certificates for those Certificates Authorities in the older Androids.

ACME CA Comparison - Posh-ACME