Q:

System.ArgumentNullException on feature enabling VERY SIMPLE Feature

I created a vs solution with :

2 Site columns
One content type
One list template
One list instance.

It compiles without any problem.
The feature packages all 4 things, IsHidden is set to true because its meant to be enabled via powershell only.
However when I enable it, i got the following exceptions in the log
Enable-SPFeature : Key cannot be null.
Parameter name: key
At line:28 char:17
+ Enable-SPFeature <<<<  "SlnOneSkyTeamsCustomization_FeatureExternalCIRCASites" -Url http://ost-dev1.ciredev1.local/
    + CategoryInfo          : InvalidData: (Microsoft.Share...etEnableFeature:SPCmdletEnableFeature) [Enable-SPFeature], ArgumentNullException
    + FullyQualifiedErrorId : Microsoft.SharePoint.PowerShell.SPCmdletEnableFeature

I install the feature like this:
# Adds and Installs the SP Solution 
Add-SPSolution -LiteralPath "D:\Sources\s\27022012\SlnOneSkyTeamsCustomization\SlnOneSkyTeamsCustomization\bin\Debug\SlnOneSkyTeamsCustomization.wsp"
Install-SPSolution –Identity SlnOneSkyTeamsCustomization.wsp -GACDeployment -Force 

# Install-SPFeature use it only after installing or upgrading the solution
Install-SPFeature "SlnOneSkyTeamsCustomization_FeatureExternalCIRCASites" -force
Enable-SPFeature "SlnOneSkyTeamsCustomization_FeatureExternalCIRCASites" -Url http://x/

Only the last line is the one that throws the exception.
on the uls logs I see also:
Key cannot be null.  Parameter name: key
Feature Activation: Threw an exception, attempting to roll back.  Feature 'SlnOneSkyTeamsCustomization_FeatureExternalCIRCASites' (ID: '4abb1043-ac29-4897-8ebc-7e01b897e6ed').  Exception: System.ArgumentNullException: Key cannot be null.  Parameter name: key     at Microsoft.SharePoint.Administration.SPElementDefinitionCollection.ProvisionFieldsAndContentTypes(SPFeaturePropertyCollection props, SPSite site, SPWeb web, Boolean fForce)     at Microsoft.SharePoint.Administration.SPElementDefinitionCollection.ProvisionElements(SPFeaturePropertyCollection props, SPWebApplication webapp, SPSite site, SPWeb web, Boolean fForce)     at Microsoft.SharePoint.SPFeature.Activate(SPSite siteParent, SPWeb webParent, SPFeaturePropertyCollection props, Boolean fForce)
Error Category: InvalidData    Target Object  Microsoft.SharePoint.PowerShell.SPCmdletEnableFeature  Details  NULL  RecommendedAction NULL
I can show the code for all files here below.
https://sharepoint.stackexchange.com/questions/30244/system-argumentnullexception-on-feature-enabling

A:

Looking at stacktrace of exception I can suppose that you have invalid XML definition for field or content type inside feature. Perphaps you are missing some mandatory attribute. Can you post definitions for feature elements?

