While doing my project on SharePoint I came across this error while deploying the feature I have created.
Error occurred in deployment step 'Activate Features': Key cannot be null
The error specifies that "Key cannot be null
". It simply means that one of the other XML field is empty or null. Before I have added content type everything was fine. Once I have added content type and was trying to deploy the same and got stuck with this. Then I checked my content type's XML very closely and realize the problem.
When we create the content type in Visual Studio, it creates the empty element which we change or we specify the value for few attributes (Here its ID, Name, DisplayName). But while deploying SharePoint does not understand this empty element but it does understand the element.
Practice makes man perfect, I am also doing the same :-).