Hi:
We recently upgraded our development boxes from VS2010 on Win 7 32 bit to VS2012 Win 7 64bit. On every legacy Net 4.0 webform solution since the upgrade, we now have the exact same problem on every box. If we open any aspx page, and modify the aspx code, every Asp.net extension (scriptmanager, updatepanel, timer etc.) becomes undefined in the designer page - however only on the open page - all other pages that are unmodified and closed are OK.
Example: Type 'System.Web.UI.WebControls.UpdatePanel' is not defined.
If we remove 'System.Web.UI.WebControls' from the control in the designer page, the error goes away. However, if we drag and drop a new UpdatePanel or other AJAX extension control onto the page, it is still shown as System.Web.UI.WebControls.XXXXX and an error appears in the designer.aspx file.
1. System.Web.Extensions is referenced, and it is the 4.0 dll.
2. targetFramework="4.0" is set in the web.config.
3. The compile target is 4.0.
4. Net 4.0 is installed and so is the 4.0 AjaxToolkit and the Extensions.
We have tried;
1. Dragging and dropping a new extension control, such as an update panel on the page and clean and recompile. Does not change the error.
2. Changing the build target to 3.5 and then changing back to 4.0.
3. Getting a stronger coffee.
Nothing works and we are at a standstill. Can anyone suggest a cure?
Thanks in advance,
Bill