9.13.10 has all of the security fixes included in 10.2.0 as was released on the same day for that reason.

The proper recommendation would still be to get to the latest version (10x.x.x) for a couple reasons.

1. The previous statement is only true as of today, if other security fixes come up in the future, they may not get backported to v9.x.x. 9.13.10 was only made possible because of a sizable anonymous financial contribution.
2. You may still encounter dependency issues anyway upgrading to v9.13.10 as some of the security fixes required dependency updates or new dependencies to be implemented.
3. We have a 2 major version deprecation policy. This means that most of the time, if an extension does not work in DNN10, it was not maintained since DNN8 days (10 years ago). So those extensions might have their own security issues.
4. A new upgrade process starting in 10.2.0 will allow us to handle those dependency conflicts in a much easier way. We are just at the beginning of that new upgrade process, but it will making those upgrades much easier.

We are here to help if you have upgrade issues. We just need more information to help. When you rollback, my flow is usually to remove any unused extension, then update all the extensions I can before upgrading DNN.
Make sure you have all the requirements met before upgrade https://docs.dnncommunity...uirements/index.html
Most of other upgrade issues, usually provide some clues in logs (Portals/_default/logs) and you can put some snippets here if you need some help upgrading.

i believe my issues are numerous in that I have some very old skins, and very old modules, some of which I need to either re-buy or just get rid of. These are pretty trivial minor sites so spending dollars on them isn't a high priority lol. My first mistake was not upgrading 2sxc and some of the other base components and skins that the sites rely on. I believe I'm going to need to revert some of these to a basic skin (which is fine none of them need to be fancy). I just need to be sure it's secure for now. I'll get around to 10x later but 10.x breaks a bunch of stuff in these skins and modules. I got 10 kinda up and running for 3 of the 4 sites, but the most important of the 4 websites was stuck in a referral loop and wouldn't come up at all (That one of course has the most customized things in it, including a 2sxc app and some other stuff. This was all developed by my excellent employee who has moved on to other things as I'm retired, so this is more a set of hobby sites than anything serious :)

For skins, most of the time it is just because they have references to now dead skinObject (notably dnn:LeftMenu and dnn:Nav). Often they are referenced but not used due to the fact that a lot of people used to start themes from a handful of common templates/starters that had references to those. It is usually easy to find and just remove. Some other commercial themes have some complex customizers that may reference more APIs that have been deprecated though, so your mileage may vary.

For 2sxc, not to their fault or DNNs fault, but there was a bit of history of having common dependencies of different versions for a handful of very common libraries. Both 2sxc folks and us have a habit of manual fixes at some versions and we are happy to help. This should get better going from 10.2.x new upgrade process to avoid those conflicts.