Was validating part of an extension I coded when I cam across some validation errors. I tested on a clean install and the issue still appeared.

Error: Attribute value not allowed on element input at this point.

<input type="file" name="fileupload" id="fileupload" maxlength="0" value="" class="inputbox autowidth" />

Error: Attribute maxlength is only allowed when the input type is email, password, search, tel, text, or url.

<input type="file" name="fileupload" id="fileupload" maxlength="0" value="" class="inputbox autowidth" />