I tried to register a customer account and was able to reproduce the same error code above as you can see below:
This typically occurs when one server on the internet received an invalid response from another server. It’s possible that the issue could be due to a temporary problem with the network or server you’re trying to access.
I would recommend you try again after a few minutes. If the problem persists, you might want to clear your browser’s cache and cookies as sometimes, this error can be related to a caching issue. If you’re still encountering the same error, it may be a server-side issue and I would advise you to contact your hosting provider.
Meanwhile, I’d like to understand your site properly. Please share with us the necessary information below for us to investigate the issue further:
System Status Report which you can find via WooCommerce > Status > Get system report > Copy for support.
Fatal error logs (if any) under WooCommerce > Status > Logs.
You could copy and paste your reply here or paste it via https://gist.github.com/ and send the link here.
Once we have more information, we’ll be able to assist you further.
You can run a conflict test, it might help to find the cause of the issue. Start by temporarily changing the site theme to Storefront and disabling all plugins except for WooCommerce. Afterwards, check if the problem still exists. If the issue is resolved, it means a conflict was interfering with the site. You can switch the theme back to its original version and start re-enabling the plugins one by one (verifying after each reactivation), to identify what could be causing the problem.