it looks like you set permission in a way so that user that runs workflows resp. effectively needs to write to history log loses permission on list item.
Actually, whoever has initiated that item is also belong to one of the approver group, but item permission didn't get assign to anyone other than authenticated users group even though it is configured for Full control to approvers.
have you checked what are effective permissions on reported item after workflow failed?
was respective user account listed there with sufficient permissions?
do you give permission to all the approver groups at once or do you give them just to a specific group that should take care of a given approval step?
Yes, we have checked the Permission after WF failed where permission got assigned only to NT/Authenticated user group and not for the approver group.
Approver group is nothing but a Collection variable which is getting loaded through the WF from another list (We observed that the variable is loaded with approver group)
so I think reason of the error is clear - permissions were not given to the group, hence user lost former permissions on an item.
so question now is why the permissions weren't setup.
can you provide more info on content of collection variable and what exactly 'approver group' is?
is it just list of user accounts you load into collection?
is it SP or AD group?
is there single element in collection or multiple ones?
if you could write collection content into log and post it might as well help.
++ what Philip said. This is likely a race condition and/or batching issue. Give this article a read as well:
