opera browser for linux

[birr]

I installed opera browser under ubuntu.  The browser will connect to some url's, and not to others.  When it doesn't connect, I get this error message:

SSL connection error

Unable to make a secure connection to the server. This may be a problem with the server, or it may be requiring a client authentication certificate that you don't have.

How would you fix this, is there some way to update opera browser so it has the correct certificates?

When I ran apt-get update, I got this

W: GPG error: http://deb.opera.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 63F7D4AFF6D61D45

I remember when I installed opera, a dialog box came up with some permissions or settings of some sort, and I changed one of them.  It had something to do with allowing something unauthorized, I think... maybe because the opera download doesn't come from the standard repos.  So now it won't update opera.  Sorry about being so vague.  If anybody can help getting this fixed, I would appreciate it.

[BADecker]

Could it be that the browser is set to protect you from sites that have expired certificates?

[birr]

I don't think so.  Opera returns that error message about half the time.  Other browsers don't.  And consider:  sites like google.com and coinbase.com aren't likely to have expired certificates.

No, something's wrong with the browser or the way it installed, or a permission, or something...

[BTCdoaA]

As all we know Firefox is highly recommended in all linux distribution else
you can use chrome 

[birr]

Firefox simply is not strong enough to run a demanding API.  I can use neither Poloniex nor the Coinbase exchange in the Firefox browser, because it freezes.
Chrome browser does the job, but Google stopped supporting Chrome browser for 32bit Linux about two weeks ago.
I can't use Opera browser.  Installation went well, but it's a crapshoot trying to use the web.  It returns SSL errors as often as not.  Unfortunately, polo and Coinbase are among the url's opera refuses to connect.