Why OnWebPageInit Can Break PHx and Built-In Modifiers

If even an empty OnWebPageInit plugin appears to break PHx tags or built-in modifiers, the problem is usually not the business logic of the plugin itself. It is the point in the request lifecycle where the parser state gets affected.

Why this is tricky

OnWebPageInit runs very early. That means even small changes to globals, parser state, output handling, or initialization order can have side effects later in template processing.

What to check

• whether the plugin really does nothing, or still changes execution context
• whether another plugin in the same event chain is involved
• whether the parser behavior differs on a clean installation
• whether old PHx patterns are colliding with newer output assumptions

When an early event breaks tags, always test the same behavior on a clean install first. If the issue reproduces there, it is probably a parser/event-order interaction, not project-specific business code.