The wf was working fine until i made few more changes and redeployed it again Below is the error i am receiving. I removed the changes and then again redeployed still same error.
Error 1 Error occurred in deployment step 'Activate Features': Microsoft.Workflow.Client.ActivityNotFoundException: The activity named 'WorkflowXaml_ac17eed9_9bdc_4aaf_9a33_eb48d306d966' from scope '/SharePoint/default/d4e22c44-37d3-40da-b0a1-0d587c1dc4ac/dc67e687-00ba-4998-bc52-0c6fc4b2e24f' was not found. HTTP headers received from the server - ActivityId: b243fbbc-dab1-4a4e-a184-b25a13eba6ae. NodeId: ------. Scope: /SharePoint/default/d4e22c44-37d3-40da-b0a1-0d587c1dc4ac/dc67e687-00ba-4998-bc52-0c6fc4b2e24f. Client ActivityId : f350acf8-e195-4cd6-b
After digging in the ULS log I found some more information
Microsoft.Workflow.Client.ActivityValidationException: Workflow XAML failed validation due to the following errors: The private implementation of activity '1: DynamicActivity' has the following validation error: Variable 'System.Activities.Variable` 1[System.Collections.ObjectModel.Collection`1[System.String]]' cannot be used in an expression of type 'System.String', since it is of type 'System.Collections.ObjectModel.Collection`1[System.String]' which is not compatible. HTTP headers received from the server - ActivityId: