rootFolder.ContentTypeOrder throws unexpected error for sandbox solution

Question

I'm trying to add content types into a library list, in order to make "Visible on New" option ticked.

Firstly I enabled contenttypes in the library, then I want to do this:

SPFolder rootFolder = list.RootFolder;
IList<SPContentType> ctList = rootFolder.ContentTypeOrder;
rootFolder.UniqueContentTypeOrder = ctList;
rootFolder.Update();

But this line IList<SPContentType> ctList = rootFolder.ContentTypeOrder; keeps throwing unexpected error:

Error occurred in deployment step 'Activate Features': 
Unhandled exception was thrown by the sandboxed code wrapper's Execute 
method in the partial trust app domain: An unexpected error has occurred.

I'm not sure if this error is related to the sandbox solution.

Related question: Content Types not visible under New Button

Answer 1

It's related to the sandbox, because you cannot use SPFolder.ContentTypeOrder and SPFolder.UniqueContentTypeOrder in sandbox :\

Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)

Available in Sandboxed Solutions: No

Edit:

If it's just to order, the code posted as an answer by James in this question might work.