Are you seeing this error on Firefox (which is common for intranet websites)?
There is two reasons for this warning.
1. You may have meddled with OCSP settings. Firefox checks Certificate validity by checking “Certificate Revocation List” (CRL) using OCSP. Firefox couldn’t get the CRL info, thus this error.
2. Your internal Certificate Authority (CA) doesn’t have OCSP installed and/or Firefox doesn’t have Root and Sub-ordinate CA Certificate in the store (Freaking Firefox has it’s own Certificate Store).
For the first issue (OCSP), you can reset the settings and fix the issue.
- In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.
- In the search box above the list, type or paste ocsp and pause while the list is filtered
- If the security.OCSP.require preference is bolded and “modified” or “user set” to true, double-click it to restore the default value of false
- Close Firefox and reopen it. Try browsing the same website.
For the second issue (no CA certificate in Firefox Cert Store), you need to add the Internal CA certificates to the store.
- Get the Certificate Authority (CA) certificate chain in P7B format. e.g., CAChain.p7b
- Open Firefox
- Open the Firefox menu from the far right side of the Firefox toolbar
- Select “Options” from menu
- Select “Privacy & Security”
- Scroll to the bottom of the page and click on “View Certificates”
- Click “Import…”
- select the certificate to add click Open and navigate to the directory you know contains the p7b certificate chain file, select the file and click “Open”
- Scroll down within the Certificate Manager window that is open and verify the certificate you imported is listed.
- click “Ok” and now you can navigate to the page you want to browse.
If this fixed it for you, leave me a reply.