It seems that Mozilla Firefox users are facing an outrage while accessing Outlook.com on their systems. The complaints of the same are from as early as Monday. Users are hitting a certificate-related to issue which is preventing them from accessing on Firefox, with some users getting the “Invalid OCSP signing certificate in OCSP response” error. Microsoft says the company has already started rolling out a fix for the issue.
Users may be unable to connect to Outlook.com via the Mozilla Firefox browser. We’ve completed restarting over 97 percent of the affected systems and we anticipate that impact will be remediated by 3:00 AM UTC on June 1, 2017. Users will continue to experience service restoration as the certificate data is refreshed across the environment.
Microsoft has already rolled out a fix and it has fixed almost 97% of the affected computers but if you’re still unable to access Outlook then just wait for the fix to roll out completely.
Let us know in the comments section if you were able to access Outlook on Mozilla or are you still facing issues with it.
Source: Office 365 Service Status