Dataverse Connector "System.ArgumentException: The key already existed in the dictionary."

[DanNewton]

We've had several flows operating in our environment for over a year without issues. These flows run daily, utilising the "list rows" action from the Dataverse connector to fetch data from Dynamics 365.

In recent weeks, there's been a gradual rise in intermittent failures, returning error 400 with the message "System.ArgumentException: The key already existed in the dictionary." However, manually re-running the flow resolves the problem.

I haven't been able to find much information regarding this specific error. Has anyone else come across it?

[LenC]

I am seeing this issue as well.

[DanNewton]

We ended up raising a ticket with Microsoft as the transient nature of this problem suggests to me it is something backend which we can't control. The ticket is going through the usual motions at the moment so I expect it'll take a couple of weeks for any meaningful response.

[LenC]

Thanks.

In my case, for a flow running every 15 minutes, it seems to happen nightly, once.  Roughly Between 11 PM and 3 AM local time.  Possibly running into some backend maintenance activities ....

[DanNewton]

Thanks, the bulk of our failures seemed to be between 8 AM and 9 AM but I have just noticed today some flows failing at 3 AM and 7 AM so this is a pretty large window if it is maintenance. Unfortunately 0 progress on the support ticket so far.

[okeks]

May I ask in which region are your effected environments located?

[DanNewton]

Hi, its UK South (United Kingdom)

[LenC]

Update: ours are happening more frequently, and happening during business hours.

My region is the United States.

[LenC]

Mine are also happening in our Production environment.

I think I have to open a support case.

[LenC]

@DanNewton I have a support chat session going. Curious: What kind of parameters are you using for List Rows?  I have multiple expansion type expressions in the 'fields' and 'expandquery' parameters....

Are your queries complex as well?

[DanNewton]

Yes, I'd say our queries are complex. We are doing some "basic" filtering with gt, ne and eq but we also use an expand query with 4 related entities. For context we are pulling data from a Dynamics 365 solution.

[TRamZ]

We are also seeing this issue. It happens on list actions using complex queries. We are in the US region.

We are also seeing SQL connection 429 throttling errors we've never seen before. The job has been running for a year without seeing these issues. I opened a ticket on the SQL throttling but the issue was not satisfactorily explained or resolved. My only option is to employ better error handling.

[DanNewton]

@LenC - have you been able to get any traction on your support ticket? Despite my ticket being open for over 3 weeks I am yet to have a meaningful update other than requests for phone calls on a ticket where the contact preference is set to email and all necessary details (including links to failed runs) have already been provided. I asked the support rep for an update over a week ago and have had no response.

[LenC · Accepted solution]

Yes, actually, I was just looking for the link to this thread....  MS Support said they identified the issue, and reported it fixed - at least for my environment.  I haven't seen it for a few days.  We just closed the case a few minutes ago.

I take it you are still seeing the issue?

[DanNewton]

We haven't seen it for a while, I was just curious given the lack of updates on our own ticket. Good news hopefully its resolved!

[LenC]

The rep on my support case believes it is "resolved for all".  I gave her the link to this thread to update if she hears otherwise.

Thanks!