PayPal Express error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handsha

I've started getting the following PayPal Express Checkout error:

(35) error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure

My site is running:
Zen Cart 1.54 (I know that I need to upgrade, but I have a heavily modified site and need to find the time to get it done properly)
PHP 5.6.34

I'm at a loss to understand why Zen Cart would be trying to use SSL version 3. As I understand it, this was completely removed in version 1.54, and the errors only just started a few days ago. Apart from product and category changes, I've not made any changes on my web site since last year. Any advice or help would be greatly appreciated.

Thank you.

Yes, as reported in this thread: https://www.zen-cart.com/showthread....yment-security

ZC 1.5.4 contains the fixes identified in that thread. It would appear that something else has changed about the server environment, most likely something along the lines of the php version, OS (operating system) or other such certificates.

The solution implemented in ZC 1.5.4 was the broadest solution that was at that time available, to allow the protocol to try at the highest level first and work it's way down until a successful connection. This was done by not identifying a specific encryption value. It is possible that the host has changed something that now implements a given value or otherwise interferes with the expected process.

It may also have something to do with a difference in payment processing code between ZC 1.5.4 and 1.5.5. I speculate on that though.

A further update on this problem. It is an intermittent problem. It occurs about once or twice per week and lasts for about an hour. Nothing had changed in my server or zencart environment for over two months prior to this problem. The problem occurred again last night and after about an hour went away. Since that time I've started receiving orders again.

This is not a Zen Cart issue.
It's an issue with your hosting server being unable to communicate securely with PayPal's servers.

"Upgrading webservers to TLS 1.2" was last year's big "buzz". You should be insisting that your hosting company put you on a capable server, or find someone else to host with.