# Connection to an OAuth data source fails with “No Error Code Provided” (Windows Edition)

**URL:** <https://community.cdata.com/t/connection-to-an-oauth-data-source-fails-with-no-error-code-provided-windows-edition/1292>\
**Category:** Editions\
**Tags:** onedrive, dynamics365businesscentral, azuread, microsoft365, article, oauth, email-send, email-receive, cdata-arc, sharepoint, microsoft-dynamics-365\
**Created:** [May 6, 2026, 9:01pm UTC](https://community.cdata.com/t/connection-to-an-oauth-data-source-fails-with-no-error-code-provided-windows-edition/1292 "2026-05-06T21:01:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![James\_B](https://sea3.discourse-cdn.com/cdata/user_avatar/community.cdata.com/james_b/32/1688_2.png) [@James\_B](https://community.cdata.com/u/James_B)\
**Post date:** [May 6, 2026, 9:01pm UTC](https://community.cdata.com/t/connection-to-an-oauth-data-source-fails-with-no-error-code-provided-windows-edition/1292/1 "2026-05-06T21:01:16Z")

</div>

I&nbsp;am attempting a new connection to an external data&nbsp;source in CData Arc. When I complete the authorization against the source, the connection fails with an error “No Error Code Provided”:

 ![f0d4d0dc-1e21-481c-9a31-080140176537.png](https://us1.discourse-cdn.com/cdata/original/2X/9/9b7c07c5fc437a48d7f1f0b4b4ff4cc78db7fe68.png)

There do not appear to be any additional logs that offer&nbsp;more insight into this error.&nbsp;This issue&nbsp;is specific to the Windows (.NET) Edition of CData Arc.

**Explanation** :

OAuth connections to external data sources in CData Arc work by authorizing access via the external data source and having the results of that authorization posted to a special endpoint in the application that processes these callback requests:&nbsp;&nbsp;/src/oauthCallback.rst

This&nbsp;error&nbsp;can occur when CData Arc is&nbsp;unable to process the callback request. The most common reason that this error occurs is that&nbsp;the&nbsp;query string&nbsp;for the callback request is longer than&nbsp;the&nbsp;default web server&nbsp;embedded with CData Arc&nbsp;allows for (2048 bytes).

**Resolution** :

**Option 1** &nbsp;–&nbsp;configure the webserver to allow for longer&nbsp;query strings:

This maximum&nbsp;query string&nbsp;length can easily be reconfigured to allow for longer requests. To make this change, locate the web.config for CData Arc in&nbsp;the \www\web.config file in Arc’s installation&nbsp;path and edit it in a text editor&nbsp;to explicitly set a longer maxQueryStringLength.&nbsp;&nbsp;Look for&nbsp;the httpRuntime element (usually line 19):

\<httpRuntime maxRequestLength=“2097151” executionTimeout=“21600” requestValidationMode=“2.0” enableVersionHeader=“false” /\>

And add a&nbsp;new maxQueryStringLength attribute:

\<httpRuntime&nbsp; **maxQueryStringLength=“8192”** &nbsp;maxRequestLength=“2097151” executionTimeout=“21600” requestValidationMode=“2.0” enableVersionHeader=“false” /\>

**NOTE** :&nbsp;Changes to the web.config will trigger a&nbsp;restart&nbsp;of the&nbsp;embedded webserver.&nbsp;While this change will take place quickly, if you wish to avoid an interruption in processing, you&nbsp;can schedule a maintenance window to apply this change.

Later releases&nbsp;of CData Arc will include the larger configured&nbsp;maxQueryStringLength by default.

**Option 2** –&nbsp;use an alternative authentication mechanism&nbsp;(if available):

Some connector types&nbsp;that support OAuth also&nbsp;support multiple authentication options&nbsp;(for example, the Salesforce connector). If this is the case, these additional authentication mechanisms&nbsp;appear under the Auth Scheme drop down in the&nbsp;connection&nbsp;configuration&nbsp;menu. Auth schemes&nbsp;like&nbsp;AzureServicePrincipalCert and AzureMSI&nbsp;do&nbsp;not use a callback URL and will avoid this&nbsp;issue.&nbsp;This option is not available for all connector types.