Custom connector Oauth problem CORS

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Posted on by Imke

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Hi experts,

I'm getting 403-error with "Invalid CORS request" in a custom connector for Zoom.:

The reason could be that call from client side instead of server side - so does anyone know how to adjust this?:

I'm using generic OAuth.
Not very familiar with the authentication options here, but if Azure AD would be an option, I'd be happy to try. But would need guidance on how to achieve that .

Thankful for any hints!

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abm abm 32,506 Most Valuable Professional on at

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Re: Custom connector Oauth problem CORS

Hi @Imke

Thanks for the update.

When access tokens expire or become invalid but the application still needs to access a protected resource, the application faces the problem of getting a new access token without forcing the user to once again grant permission. To solve this problem, OAuth 2.0 introduced an artifact called a refresh token. A refresh token allows an application to obtain a new access token without prompting the user.

Did you set the refresh URL. Set the link same as Token URL.

If all running as expected please mark the solution as expected.

Thanks
Imke 281 on at

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Re: Custom connector Oauth problem CORS

Hi @abm
just a quick update: I've deleted all existing connections for that custom connector and then was prompted to login again when triggering the flow again. Worked fine.
Scheduled for every 15 mins now and its still running OK. So maybe the problem is solved now.
Imke 281 on at

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Re: Custom connector Oauth problem CORS

Hi @abm
wondering if you also have an idea about the latest error-message:
Do I have to refresh or reset the connection in flow somewhere?
Thanks a lot !!
Imke 281 on at

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Re: Custom connector Oauth problem CORS

Hi @abm
sorry, I missed your first message.
Thank you so much, it finally worked!! At the end I had to build a new connector, but yeah - now it's working as expected in the flow itself (same error messages like you during testing…)
abm abm 32,506 Most Valuable Professional on at

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Re: Custom connector Oauth problem CORS

Hi @Imke

Did you tried the below suggestion? Please let me know.

Thanks
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abm abm 32,506 Most Valuable Professional on at

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Re: Custom connector Oauth problem CORS

Hi @Imke

I did tried creating a custom connector for Zoom. Here are the details:

Here is my Authentication type I used

Above I have set Refresh URL is same as Token URL

Here is the method I was trying to test

This is my test result:

So here I have replicated your error. I did tried with different things around and tried the same in POSTMAN using OAuth2 using client Id and Client Secret. Managed to generate a Bearer token via Postman and here is the result:

So this confirms that CORS error is nothing to do with the credentials or headers. Next what I tried is created a Power Automate action step using the current test connection and I got a different error saying invalid token.

That indicates me that something in that test connection is not quite right. So what I did next is create a new connection.

As you can see above I created a new connection by clicking Add new connection.

Run my flow and here is the test result:

So try creating a new connection in your Power Automate action step. That should work as expected. I am not sure why the test failed under the custom connector.

Please let me know how it goes.

Thanks