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Intermittently get 'An unknown error occurred' on Sharepoint List Lookup...connection then lost

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Posted on by Community Power Pla... Microsoft Employee

We are getting an intermittent error "An unknown error occurred" after entering a barcode number which does a lookup to a Sharepoint Online List. The lookup fails (producing a message generated by the app that "There is no tool with this barcode") and the connection to the Sharepoint List is gone and cannot be recovered. App has to be restarted and once it has been the Tool checkout transaction can be done successfully.

I have checked that the PC still has internet connectivity (it does), and though the symptoms appear to be the same if I disconnect the network cable, that does produce a more meaningful message about failing to contact the server. I'm wondering if there is some timeout somewhere that we are hitting and the connection just closes? This happens multiple times a day.

I have another PowerApp that I developed recently that is using Sharepoint Lists from the same site and is also in use all day by multiple users and that app is not having this issue.

Does anyone have any ideas what could be causing this?

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Community Power Pla... Microsoft Employee on at

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@anees @v-micsh-msft Microsoft staff - can you please provide some assistance on how I can diagnose an intermittent error that I cannot reliably reproduce when all I get is "An Unknown Error Occurred"? How can I get support on this? This is the session ID of a session where a submit failed at about 4:08pm New Zealand Time today:
This app is failing intermittently anywhere in the app where a read or write to the Sharepoint list occurs. The connection to the Sharepoint List just appears to be dropped, but the PC's connection to the internet is still working. This is a LIVE application that is failing and not providing sufficient information to understand why. Please help.
v-monli-msft Microsoft Employee on at

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Hi @Anonymous,

Have you tried to delete this connection inside the app and then readd it again? If this doesn't work, please check on the PowerApps connection list site, make sure that this connection's status is Connected. If not, fix the connection there.

Regards,

Mona
Community Power Pla... Microsoft Employee on at

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Thanks for getting back to me Mona. Yes, the connection has been re-added in the app and app republished but this intermittent issue keeps occurring. The app starts up and works for hours and then the connection appears to just drop off and the app starts to fail on a data lookup or write but with unhelpful error msg. The app has to be shut down and restarted to get the connection back. Refreshing the data connection within the app doesn’t help.
Does “the PowerApps Connection list site” show the status of connections for different sessions of the app that are running? As the app is being used by someone at a separate location to me, am I able to see what is happening to their connection if they let me know when the app fails, or does someone need to look at this on their PC? How would I fix the connection there? Can you point me to support documentation about this? Thanks, Anne
Community Power Pla... Microsoft Employee on at

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Hi Mona @v-monli-msft
We are still having this issue. I see another thread that appears to have the same issue:
https://powerusers.microsoft.com/t5/General-Discussion/Data-connection-timeouts-without-error-or-warning/td-p/51316

Is this a known issue? Is Microsoft looking at this issue?
anees 250 Microsoft Employee on at

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@Anonymous checking to see if anyone knows why this may be happening. Will get back.

- Anees
Community Power Pla... Microsoft Employee on at

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Hi @anees,
Any progress on this? Is there any information that you need from us to help investigate this?
Or do I need to log a support ticket about this?
Thanks,
Anne
Community Power Pla... Microsoft Employee on at

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Hi @anees,
Just thought I'd add that we seem to get this error message if trying to write to SharePoint when the connection has "dropped off": "There was a problem saving your changes. The data source may be invalid".
Why is our data source suddenly invalid when it has been fine for hours, and the internet connection is still up? We restart the app and then it's fine again.

Would appreciate some assistance with this issue, as having an ongoing intermittent fault does not make the PowerApps environment look stable.

Regards,
Anne
anees 250 Microsoft Employee on at

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@Anonymous, I mentioned this to @AlanC and looks like he was following up on the linked thread.

@AlanC can you please reach out to @Anonymous as well?

Thanks
Anees
AlanC Microsoft Employee on at

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Hi @Anonymous, I took another look to the telemetry, I see a lot of errors calling to SharePoint with a 429 response:

{
"statusCode": 429,
"message": "Rate limit is exceeded. Try again in 5 seconds."
}

What this error means is that this particular connection is making a lot of calls in a very short amount of time, it looks like your app has a lot of burst in which it makes between ~100 and 200 calls per second, this is very unusual.

I can't tell from telemetry what your app is doing to be causing so many calls. One possibility is that you may be making a call per item after a refresh, for example a scenario that would cause this behavior would be to have a ForAll call after a Refresh that uses the value from one of the item's properties to make a call to another data source. My suggestion would be to modify your app to avoid making so many calls at the same time, unfortunatelly without the specifics of your app I can't give any specific suggestions.

Thanks,

Alan
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Hi @AlanC,
Thanks for looking at this for me. It is not immediately obvious to me why the app would be doing that. Are there any steps that I can take to get more information about the calls that are being made?

Regards,
Anne