Firefox upgraded to version 33.0 this morning. Since then, I cannot load a specific local application over HTTPS -- note that it uses a self-signed certificate. It displays the following error message:

`The key does not support the requested operation. (Error code: sec_error_invalid_key)`

I cannot see anything in Firebug. I restarted Firefox in safe mode, to make sure no add-on was the problem. I also cleaned my cache and cookies. The same application opens fine with Chrome, and Firefox can open other applications that use HTTPS with a self-signed certificate.

Any idea how I could troubleshoot this issue?

**Edit:** Mozilla has made several important changes to security in Firefox 33.0. Details can be found [here](https://developer.mozilla.org/en-US/Firefox/Releases/33/Site_Compatibility#Security).

In my particular situation, the self-signed certificate was blocked because it was deemed too weak:

> 
> RSA 512, 1000 and 1023-bit certificates are now blocked by Firefox since they are not sufficient for security. Most certificates currently being issued should have a 2048-bit key length.
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