I'll begin with the background of what I'm trying to accomplish. The system has a working workflow already, what I want to do is edit the workflow to meet some new requirements - so far I have only made a simple change to some text output to test.
I made the change through SharePoint Designer and then followed the instructions in the link below;
https://msdn.microsoft.com/en-us/library/office/jj819316.aspx
It worked as expected up until the activation of the feature. I have went through the usual steps clearing the cache etc but no matter what I can't seem to get past the error.
The workflow was exported from SP Designer as a WSP and uploaded to SharePoint.
Does anyone know of a way of forcing the activation of the feature?
Alternatively, advice on editing existing workflows would be appreciated
EDIT 13/08/15: Having followed Susan's advice I looked further into why the workflow wasn't updating via the publishing feature. I changed the site in designer to the actual sub site and made the changes there. This worked!
I thought that making the changes at the top level would automatically update all of the sites but this was not the case.