Validation - is rendered item valid xhtml - Exception -

when validation on page in sitecore 7, validation throws exception :

the page represented item 'home/about-us' failed render properly. error     : remote server returned error : (500) internal server error 

i didnt expect page render valid xhtml, did not expect exception validation.

does have idea, why exception thrown?

thanx

i've encountered issue , found wasn't page mark-up invalid rather, sitecore validator doesn't handle errors enough provide useful feedback end user.

how xhtml validator works (out of box)

1. build friendly url of current item (with parameters handle language, device etc.).
2. create web request combined url , retrieve page (this error comes from).
3. download response , send off w3c validator (there more logic around here however, it's not cause of op's issue).
4. return validation information user.

so why break?

if web request above fails validator fail however, won't give detailed reason why (you exception message when need inner exception message). fails log sitecore logs.

how fix xhtml validator issues

you're server probably isn't configured correctly allow web requests itself. here quick ideas may you.

1. check have valid ssl certificates if you're using them (self-signed won't work).
2. check you've set server proxy correctly.
3. check server not url re-writing requests in strange way.
4. create new implementation of sitecore.data.validators.itemvalidators.fullpagexhtmlvalidator based on original, update validator item in sitecore use you're new validator , run debugger on it.
5. disable xhtml validator (this depend on requirements implementation).