Workflow with id not found in persistance store

For couple of days now I've been doing extensive debugging of a (Windows) Workflow. And time and again I've been facing this error. So I thought I will elaborate more on this. There are three primary reasons why this might happen:

1. Your workflow has actually terminated. It could have terminated or finished execution, but since you wouldn't try to load a finished workflow, in all probablities, it would have terminated (due to some unhandled exception). You can check this by going to your WorkflowInstance table in your persistence store and check the DbEndDateTime for your workflow instance. If it is null, then you can move to next points :-) else you have found the culprit. All you have gotta do is to debug into your workflow and fix your code.
2. Workflow changes. If you make any changes to your workflow and then try to load previous instances of it, you will see this error. You will have to apply the changes done on the workflow to the old instances also.
   
3. Try to connect to remote persistence store. If you are trying to load a workflow instance from a remote store, this error will come up. Make sure that your remote (store) server DTC is configured to allow this.

Hopefully, this will help people in saving time trying to find why the workflow doesn't load. Pls be aware that this error can come up due to many other reasons and not only the three mentioned above.