inputfield error allowmarkup not working

[swissdoode]

First: I'm using PW 2.x for this (don't ask)...

I'm trying to output an error with HTML-Markup, using this:

$form->get($errField)->error($exception->getMessage(), Notice::allowMarkup);

But the HTML-Markup that's in $exception->getMessage() is rendered with HTML-special chars.

What am I doing wrong?