Disabling mod security worked. But how does that affect the security of my site?
And also, for my knowledge, I have other sites on this server running the same configuration (J5, SPPB 5.2.6, Helix 2.0.18, php 8.1, mysql 7.4.33), but were created from a clean install versus an upgrade. Why does this make a difference?
Also, can I turn off mod security to save settings, and then turn back on when complete? It doesn't seem to affect anything once the template changes are made and mod security is turned back on.