hi, are you using avast security software on the affected system by any chance?

Hi Philip. No I do not have avast security software installed. I'm using an iMac. John

ok, the problem i usually caused though when something on the system or network is intercepting/meddling with encrypted network traffic though. could you run a test and see if the problem is still occurring when you enter about:config into the firefox address bar (confirm the info message in case it shows up), search for the preference named security.tls.version.max and then double-click it and change its value to 3 - this is only for diagnosing the matter and no permanent solution as it will decrease the strength of secure connections in the long run...

OK, I did all that decreasing the value from 4 to 3. I am logged into Spotify but when I try to download the desktop app, I keep getting the same Error code...

hm, in this case i'm starting to run out of ideas slowly. in any case you should go back into about:config and reset that preference to its default value 4. do you know of any other proxy/vpn software on your system or network that might cause interference with network traffic?

Thanks for your advice. I'll have to forego Spotify on my desktop. Still, I have it on my phone, not all bad! John

Did you close (Quit) and restart Firefox after modifying security.tls.version.max ?

Sorry about the delay in replying to your last post. I had not closed down and restarted. Just did so and all is well. Thanks for your help, much appreciated.