We have created a 2013 workflow and trying to deploy it in the QA environment as sandbox solution.

This is when we are getting an error. In QA we have checked that the Workflow manager is configured correctly.

Application error when access /_layouts/15/ManageFeatures.aspx, Error=System.NullReferenceException: Object reference not set to an instance of an object.  

 at Microsoft.SharePoint.WorkflowServices.WorkflowDefinitionStorageEventReceiver.PublishDefinition(SPItemEventProperties properties) 

 at Microsoft.SharePoint.WorkflowServices.SPWorkflowPackageFeatureReceiver.FeatureActivated(SPFeatureReceiverProperties properties)   

 at Microsoft.SharePoint.SPFeature.DoActivationCallout(Boolean fActivate, Boolean fForce)   

 at Microsoft.SharePoint.SPFeature.Activate(SPSite siteParent, SPWeb webParent, SPFeaturePropertyCollection props, SPFeatureActivateFlags activateFlags, Boolean fForce)   

 at Microsoft.SharePoint.SPFeatureCollection.AddInternal(SPFeatureDefinition featdef, Version version, SPFeaturePropertyCollection properties, SPFeatureActivateFlags activateFlags, Boolean force, Boolean fMarkOnly)   

 at Microsoft.SharePoint.SPFeatureCollection.AddInternalWithName(Guid featureId, Int32 compatibilityLevel, String featureName, Version version, SPFeaturePropertyCollection properties, SPFeatureActivateFlags activateFlags, Boolean force, Boolean fMarkOnly, Boolean fIgnoreMissing, SPFeatureDefinitionScope featdefScope)   

 at Microsoft.SharePoint.WebControls.FeatureActivator.ActivateFeature(Guid featid, Int32 compatibilityLevel, SPFeatureDefinitionScope featdefScope)   

 at Microsoft.SharePoint.WebControls.FeatureActivatorItem.ToggleFeatureActivation()   

 at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)   

 at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Have you checked the site features and ensured that all relevant information has been enabled in the sandbox site ? Specifically Publishing and the Workflows can draw from Applications/Webparts feature.

Can you please help me by listing the features?