With MAGNOLIA-6025 the handling of encoding-issues in parameter and selector values was modified. Before the patch, magnolia responded with a HTTP 500 Error-Code, after the patch with a HTTP 400.

Unfortunately, this error can not be handled internally, for example by responding with a page from website. In web.xml you can only set an external ressource.

<error-page>
	<error-code>400</error-code>
	<location>/errors/bad-request.html</location>
</error-page>

This behavior differs from the handling of HTTP 404 and should be adapted.