Broken DatePicker Calendar Popup

Question

I'm having problems with the DatePicker in SP2013. The control shows fine, but the calendar popup is broken because of a missing stylesheet (the complete sprite sheet image is visible etc.).

The css missing is corev15app.css. It should have been returned by the _layouts/15/defaultcss.ashx handler called in the calendar iframe source, however this fails. Here is the related log output:

defaultcss.ashx: resource specified null
defaultcss.ashx: attempting to get web.MasterCssUrl
defaultcss.ashx: using elevated codepath to get css file or other resource because the non-elevated code path failed to get it. (...)
defaultcss.ashx: attempting to get web.MasterCssUrl
Application error when access /_layouts/15/defaultcss.ashx, Error=The object specified does not belong to a list.

Additional info: I upgraded a SharePoint 2010 solution, set up new layout pages and used the new seattle master page from SP2013. Just about everything works as it should. However the DatePicker and the "Add an app" page (addanapp.aspx) fails. The app page just stops with the loading animation.

Answer 1

It seems that the problem arise when your master pages are not located in the Master Page Gallery. The problem went away when I added the master page to the master page gallery and referenced it from there (i.e. _catalog/masterpage/mymasterpage.master) instead of the _layouts folder. The actual server deployment location of the master page is still in the layouts folder (could also be the feature directory itself).

I added a new module that adds the master pages to the site collection gallery, updated code that sets default master page and that fixed the tedious datepicker calendar problem.

I speculate that this might be related to new security measures regarding iframes (the datepicker control pops up an iframed calendar).

Answer 2

I had a similar issue with a custom Master Page I created in Design Manager.

To fix, I created a new Minimal Master Page from scratch, tested that the datepicker worked, then copied my HTML and Style Sheets to the new Master Page.