Upgrading PrestaShop (1.6.1.2 > 1.7.6.4)

[SparkyRih]

So, I've ignored upgrading my store for years now, mostly because I stopped due to other projects. About a year ago I "restarted" the business, and started using my webshop again. But now it's time to completely refresh it, and first thing to do is upgrade it.

 

So I'm currently running version 1.6.1.2 on PHP-FPM 5.6. I maintain my own server and my primary PHP version is 7.2 (so I can switch with one click of a button to this version of PHP).

 

However, PrestaShop 1.6.1.2 does not seem to run on PHP 7.2, so my question.

What's the best way to start upgrading? Are there key versions which I can upgrade to first, for example: Upgrade to PS 1.6.1.10, then switch to PHP 7.2, and than upgrade to PS 1.7.6?

 

Any advise on what to do?

[Knowband Plugins]

Refer to PS compatibility chart on the URL below.
https://devdocs.prestashop.com/1.7/basics/installation/system-requirements/

We believe PHP1.7.6 can run on the PHP5.6 so do the upgrade on PHP5.6 (FROM PS1.6 to PS1.7) & after upgrade you can switch the PHP version (So no need to intermediate upgrade)

 

[SparkyRih]

I did an upgrade attempt yesterday, but I'm getting stuck with this error:

 

"classes/PhpEncryption.php line 116 - Call to undefined function openssl_get_cipher_methods()"

 

My php.ini (of PHP5.6.30) appears to be configured correctly.