When trying to view the workflow history of an item I get the following error: "Error Occurred. Unable to preview workflow".
I am able to see the detailed view of the workflow just not the diagram view of the workflow (where the icons turn green when completed, etc...). There has been no changes to the workflow and the issue only applies to workflows created in 2016 (so not sure if that has something to do with it).
Things that I have checked which could potentially cause this issue (according to other posts):
Any help welcomed
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Can you check exactly when that workflow instance ran?
Usually, this is an issue someone has purged data from the Nintex Workflow database, either going through Central Admin > Nintex Workflow Management > Purge Workflow Data or using the command line tool NWAdmin.
Are you sure no maintenance has been done on the database?
If you were to create a simple workflow right now, that just has a Log in the History List action, publish and run it, can you see the workflow history?
I am sure the permissions are fine as my admin credentials are able to see other workflows and can see the workflows pre-2016. I thank you for your thought though
Thanks for your response Vadim,
Interestingly I just went to check when the instance's run last and it now seems that I am unable to view any of the workflow history in 2015 also (which was only effecting 2016 a few days ago). I can still see the history going back to 2012.
I checked purge workflow data and it is set to "where the list or library has been deleted", which it has been for a very long time.
I can confirm that no maintenance has been done on the database (I have also checked this with my DBA).
I have 2 workflows set up currently and the first one is very small and the second one larger. I am able to view the history of all the small workflows but not the large.
Any thoughts? It seems like it is spreading backwards over time.
There's one other thing to check. What does your workflow look like? Is it built in such a way, that it is all inside an actions like an Action Set?
There is a setting in all actions, under the Common button in the ribbon of the action configuration, that says "Don't log Workflow Status". If that happens to be checked, it wouldn't log anything to the database, and as a result, there's be no visual workflow history. This is just a guess.
The only other thing I can think of, is that the query that pulls the data from the database, is freaking out about something. This isn't something I've seen before, so maybe there is an error in the SP logs that could explain why this isn't working.
Thanks once more for your reply Vadim,
I have taken a look and I cannot see the "don't log workflow status" check box so I don't believe it to be that.
That seems logical I have trailed through the logs many times and not come across anything but I will continue to look.
It is certainly complexing that in Dec15 I could see them all fine. Mid Jan16 I am unable to see all 2016 workflows (rest are fine). Late Jan16 I am unable to see any 2015/2016 workflows (rest are fine).
We had the same error today. Sometimes the workflow history showed that error and at some time it disappeared again and the workflow worked again.
In our case our customer tried to set a list field of type boolean with a text variable containing the string "yes" or "no". As we recreated the workflow variable as a yes / no variable and updated our list column with that column's value the workflow worked like a charm.
I think the wrong true / false string set in the column confused either SharePoint or Nintex Workflow or both and caused the error.
Maybe your problem is kind of related to that.