Hello,
Thanks for the kind words, and I hear the frustration. Two months is a long time to spend on an upgrade.
To clarify one thing: using Chevereto self-hosted will always require some systems knowledge (server setup, file permissions, database access, etc.), since you're responsible for the hosting environment. That's different from programming knowledge, which is genuinely not required to run or upgrade Chevereto.
It's also worth noting that upgrading will always be harder the older the release you're coming from.
V3.15.2 was released on 2020-05-16, and over a span of time like that, several dependent systems (PHP, MySQL, your OS, and so on) will also need upgrading alongside Chevereto itself. That compounding is often what makes these jumps feel so much bigger than a normal update.
We're always working to make major upgrades smoother, and feedback like yours helps us prioritize that. In the meantime, if you'd rather not deal with the systems side at all, we offer support services that can handle the upgrade for you, often far cheaper than the time cost of doing it yourself, and without the frustration.
Thanks again for sticking with Chevereto since V3.15.2, and for the encouragement!