How to fix "Validation(): Element 'xxxx' is not supported" and "Unrecognized tag prefix or device filter 'asp'"
Since about a month ago,I started to get validation warnings
at design time on asp.net server controls (any control
actually) within the html design view for VS 2010 or
later,intellisense on all controls would not work at all,the
messages like:
Unrecognized tag prefix or device filter 'asp'
Validation(): Element 'Label' is not supported.
Validation(): Element 'GridView' is not supported
....etc
The compilation done successfully but the warnings still
exist and intellisense is not working at the source tab
I tried to reset the settings of Visual studio ,disabled all
extensions and few other ideas but none of them solved the
issue,I got stuck.
I did a search over the internet about this issue and found
this article on
Doug Kennard's blog:
http://www.gotknowhow.com/articles/fix-validation-element-not-supported-visual-studio-2010
Splendid,that article is a life savior,the idea is to remove
the folder "ReflectedSchemas" from paths:
Win XP : C:\Documents and
Settings\{username}\Application
Data\Microsoft\VisualStudio\10.0\ReflectedSchemas
Win Vista / 7: C:\Users\{username}\AppData\Roaming
\Microsoft\VisualStudio\10.0\ReflectedSchemas
Note: make sure that
"Show hidden files, folders, and drives" is selected
from Folder Options,also don't forget to close VS
before deleting the folder.
This solution should work for any Visual studio version,keep
in mind that you have to use the correct VS version number
i.e
Visual studio 2010 :
%appdata%\Microsoft\VisualStudio\10.0\ReflectedSchemas
Visual studio 2012:
%appdata%\Microsoft\\VisualStudio\11.0\ReflectedSchemas
Visual studio 2013:
%appdata%\Microsoft\VisualStudio\12.0\ReflectedSchemas
..etc