Hello, i was reading some guides to add some stuff, and i noticed that i could lose all my template changes when i upgrade to a new version of xen foro, is that true? How i can prevent, dont lose everything?
For now, all changes are small, but if i keep editing it i dont wanna lose everything what i alread did
No - Templates that are changed are skipped. Upgrades do not overwrite your custom templates. They must be manually reverted to get the new features from an upgrade, then you must merge your custom changes back into the reverted template.
This is one of the many reasons you shouldn't have debug mode on if you don't know the caveats of the additional features it exposes. (And you should never have it globally enabled on a production site.)
What are outdated templates and why do I need to revert them? Can't I just continue using the old ones?
If a template is changed between releases, i.e. from 1.0.0 to 1.0.1, and you have manually edited it, then it will be marked as outdated. This is done because the software doesn't automatically overwrite those templates, thereby causing certain functionality which you have added to be lost. It is an indication that the core code has changed and you need to take action. The software will continue to function with these outdated templates but you may be missing important updates and bug fixes so it is recommended to revert and reapply any edits.