The major problem is that even I tried to restored the old version, the new changes should be discarded, but the same error still exist when I want to publish an older version.
The changes I made recently can be discarded, I just want to restored back to a workable older version.
I followed the step to open the older version in this post.
is it a list workflow?
haven't you changed datatype of a field in list the workflow is running on?
or in some other list that the workflow may work with (eg. query list, update items, etc)?