The error.phtml generated by Zend_Tool, unlike the other view scripts, tries to pass itself off as being XHTML 1.0 Strict - however brave an attempt, the doctype that is produced is invalid. There are two issues with it:

1. There should not be a ; between the two parts.
2. The final double-quote is missing.

To fix this, change the doctype in error.phtml from: "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd> Into: ofollow" href="www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

Validator error for the semicolon: character ";" invalid: only delimiter ">", delimiter "[", system identifier, "CDATA", "NDATA", "SDATA" and parameter separators allowed