Showing results for 
Search instead for 
Did you mean: 

Flow runs ok, but cannot view history



I have a HTTP reuqets trigger-based flow, which then uploads a file to Azure blob storage. Flow seems to work, although we cannot be sure because we get an unexpected error when trying to view the flow output. The error is as follows and here is the correlation ID for you to follow-up.


Any ideas?


Server/Client Correlation ID: fc43e92f-7cf0-4078-953b-a2f982054005

Error: Unexpected token � in JSON at position 0


Server/Client Correlation ID: 1ed2cb71-b714-4d02-bcf7-03ac5d46034b

Error: Unexpected token � in JSON at position 0




Paul Culmsee


I don't know if this related or a regression bug, but I notice flow has changed now, particularly around using workflow definition language. To that end, check out these screenshots...


FIrst up note how I added the base64tobinary() function to a file received by flow... 




So I click "Update" and when I open it again, my function is gone...




Am I doiing something wrong?



Not applicable

can easily reproduce this bug.  export to json looks ok.  But the UI has gone stupid and forgot the outer base64ToBinary() 😞



Also see this error, and even on flows with a Successful status...


Server/Client Correlation ID: 5837bf9d-c1ff-4cca-9937-7f28f9c491ff
Error: Failed to read



Okay definitelly a regression bug. I have an older flow that previously had no problem checking the history of it. I just checked it today and I see same problem...


Server/Client Correlation ID: 1a06b9a8-42aa-4315-aff8-cd9df8f81b3d
Error: Failed to read.


Just to be clear, this is a flow I have been using for a while now. The history summary shows successful runs, but as soon as I click one of the flows I get the above error.



I can reproduce this now and it does appear to be related to the case of the dissapearing function (see the second post in this thread). 


Basically as soon as I use a compose action with the base64ToBinary function, I get an error when trying to view the flow, whether it runs successfully or not. If I remove the compose action, I can once again view the flow output...



Hi paul_culmsee,


For updating the expression, you need to first update the expression and then click to update the flow. Let me if that works.





So I checked this by exporting the flow and then checking the file, as did @Anonymous. WHen I check the flile I see the full expression as I typed it, but in the UI I do not. 



Hi Paul,


I just checked with others about base64ToBinary disappear problem. It's because binary format doesn't compatible with the field type. Most of our fields accept string, number, boolean, etc. So maybe you need workaround for it. For the flow run showing error page issue, thanks for reporting it. We are working on it, it would be fixed soon.



Glad to see the flow error is being addressed. That is the issue that is causing me grief...


This function takes a base64 encoded string as input and returns binary, so it is actually a string.


This function is actually working, because if I remove the Base64ToBinary function my flow works (and the status page displays), but the attachment is malformed when I mail it or store itt.


If I add the Base64Tobinary function, the workflow history error happens, but the flow still works and my file is now not malformed anymore when I mail or store it.


Hence why I think the two issues were related.... 

Helpful resources

Community Conference

Power Platform Community Conference

Check out the on demand sessions that are available now!

Power Platform ISV Studio

Power Platform ISV Studio

ISV Studio is designed to become the go-to Power Platform destination for ISV’s to monitor & manage published applications.

Top Solution Authors
Users online (15,603)