Page error when Development mode enable

Dear,

I am using T3V3 version 2.1.6 with tpl_t3_bs3_blank. The problem is happen when I enable the development mode. The web page become not display or blank page. However when I disable the dev mode, the page back to normal display.
I tried to checking it on Title , then the result are 6 Errors, 4 warning(s). Below are the results :

Using experimental feature: HTML5 Conformance Checker.
No Character Encoding Found! Falling back to UTF-8.
No Character encoding declared at document level
Element head is missing a required instance of child element title.


Element name jdoc:include cannot be represented as XML 1.0.

Element jdoc:include not allowed as child of element body in this context. (Suppressing further errors from this subtree.)


Self-closing syntax (/&gt used on a non-void HTML element. Ignoring the slash and treating as a start tag.


End of file seen and there were open elements.


Unclosed element jdoc:include.

Need your help to solve this problem

Kindest Regards