Showing results for 
Search instead for 
Did you mean: 

Custom Connector $filter query string parameter does not work

Hello experts,


I've just setup a custom connector. Problem I'm facing is the $filter query string parameter does not seem to be properly working.


During connector testing all is good, I get a 200 response, expected results. When I go to run the actual flow and pass the exact same $filter string parameter value, I get a 400 error saying the data types are not compatible, see below. Very strange that the custom connector testing does not match the actual flow when being it possible some characters are being automatically escaped in the custom connector testing area but not in the actual flow? I've tried encoding, using compose variable string, etc but I'm stuck. Please help, any advice/input is welcome!


Testing - 200 response


Flow run - 400 response




First, your filter seems like using an exact timestamp. Due the nature of distributed systems a match on exact timestamp may proved to be tricky. Try using a window instead or some other criteria to filter on.


Secondly, can you tell us more about how you implemented $fliter in your custom connector and how is it processed in the backend? If you can explain what you are trying to do with this flow in general that will be helpful too.


Thirdly, compare the differences between the test environment and prod environment. What are the difference between the two? Are the backend changes same in both prod and test? Can you make the API call using an app such as postman and get same/different results? Testing with postman can be helpful, since it will validate if you backend is returning correct results with the query or not. Once you confirm that, the only remaining thing to check is the connector itself.


Hope this helps.

If this reply answers your question or solves your issue, please ACCEPT AS SOLUTION ☑️. If you find this reply helpful, please consider giving it a LIKE 👍.


The problem may be odata specific. Try googling for the error message. Please take a look at this see if it helps:


If this reply answers your question or solves your issue, please ACCEPT AS SOLUTION ☑️. If you find this reply helpful, please consider giving it a LIKE 👍.


I've been struggling with exactly this, testing different odata filters to see if they there some difference between the testing stage and prod flow - maybe testing stage adds some header or character I don't see?

FYI When I try filtering on another field eg like a text field it seems to work ok. I've also tried passing the filter string first as a PA variable but I have the same issue.


Thanks again for the input.

Thanks for the response and appreciate the help.


1 - So I have a test version of the API, and I used a specific DateTime in my post above to get an expected result, using Postman. I just changed the filter to a datetime window and got 6 results in the testing stage of the connector and also in Postman...but still get an error in the prod flow that the type entered is not correct.


Makes me believe that the prod flow adds some extra characters or the test flow is adding something eg additional header or escaping characters.


Testing Connector



Postman (same Get Request)



Prod PA flow



2 - The $filter in the connector is setup as a optional, string. Eventually I was going to use this data to return only the last records modified in the last 1 day. Not sure if I'm missing any configuration here. I left the default empty so I could pass dynamic string value.




3 - The setup for the connector and the flow are the same, point to same endpoint/gateway/etc and the test connection results match Postman exactly (above).


Still struggling with this, any ideas why the testing environment returns data properly but not in an actual flow?


I wouldn't think the test and prod would behave differently. Are you using the same backend API for test and prod?

Helpful resources

UG GA Amplification 768x460.png

Launching new user group features

Learn how to create your own user groups today!

Community Connections 768x460.jpg

Community & How To Videos

Check out the new Power Platform Community Connections gallery!

M365 768x460.jpg

Microsoft 365 Collaboration Conference | December 7–9, 2021

Join us, in-person, December 7–9 in Las Vegas, for the largest gathering of the Microsoft community in the world.

Top Solution Authors
Top Kudoed Authors
Users online (1,715)