Is there a way to make Firefox ignore invalid ssl-certificates?

Question

I am maintaining a few web applications. The development and qa environments use invalid/outdated ssl-certificates.

Although it is generally a good thing, that Firef

Answer 1

Go to Tools > Options > Advanced "Tab"(?) > Encryption Tab

Click the "Validation" button, and uncheck the checkbox for checking validity

Be advised though that this is pretty unsecure as it leaves you wide open to accept any invalid certificate. I'd only do this if using the browser on an Intranet where the validity of the cert isn't a concern to you, or you aren't concerned in general.