How to fix “’Activate Features’: System.NullReferenceException: Object reference not set to an instance of an object.” when deploying SharePoint2013 workflow
I encounter the following error when trying to deploy the SharePoint2013 workflow using visual studio 2012 and the error message itself does not really explain why it happened.
After I put some time to think why this could happen, I figure out it is because you either do not configure your windows Azure workflow or forgot to register your site collection with window azure workflow.
To configure the workflow you need to check this MSDN article How to: Set up and configure SharePoint 2013 workflows
To check your site collection is registered properly with window azure workflow. Run the following PowerShell command
If it returns true, the configuration is good
Otherwise you need to run the following to configure register your site. You need to adjust your url in the following script for your environment.
Register-SPWorkflowService –SPSite "http://sp2013" –WorkflowHostUri "http://localhost:12291" –AllowOAuthHttp