Setting default headers causes concurrent access errors (E_CHANGED_STATE)

[martinraiberfc]

Setting default headers before using a httpclient causes concurrent access errors (E_CHANGED_STATE: A concurrent or interleaved operation changed the state of the object, invalidating this operation.).

To reproduce see following example: https://gist.github.com/martinraiberfc/46ad7fc6e5c6e2516f09f78d1e234f3e

This perhaps needs to be documented or somehow fixed. As a work-around the headers can be set via a custom request filter.

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Document Details

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• ID: b195d006-dff9-0a63-7008-3f50887c3be9
• Version Independent ID: a2f8a231-97e4-6f69-7100-93e19171ecb5
• Content: HttpClient.DefaultRequestHeaders Property (Windows.Web.Http) - Windows UWP applications
• Content Source: winrt-api-build/xml/Windows.Web.Http/HttpClient.xml
• Product: uwp
• Technology: winrt-reference
• GitHub Login: @stevewhims
• Microsoft Alias: stwhi

[stevewhims]

Thanks, @martinraiberfc. I'll investigate whether the behavior is considered a bug or not.

-Steve

[stevewhims]

UPDATE: Thanks for your patience: we can't reproduce the issue as described. So I'll go ahead and close this for now, but we can reopen if it different data comes in.

Thanks! -Steve

[JunielKatarn]

@stevewhims FYI. We have encountered this bug while developing a feature for React Native Windows. Had to implement a workaround.

The bug is intermittent, but we'll try to come up with a consistent reproducible case.

[uroni]

@JunielKatarn How did you workaround this issue? We worked around it by setting the HTTP headers in each request. The problem is that I guess that makes the multi-threading bug just harder to hit and we are currently running into this with wider testing.