How to resolve EdgeDriver error with Selenium Testing WebView 2 - Only ASCIIZ protocol mode is supported

PhilC 0 Reputation points

Hi Guys,

Since version 117 of the edge webdriver we have been seeing the following error:

OpenQA.Selenium.WebDriverException : unknown error: only ASCIIZ protocol mode is supported

We have been putting together a large, automated test suite using Selenium to test a react site hosted within a webView and it has been working perfectly until we updated to version 117 of the edge driver. Our company pushes updates of Edge and the Edge WebView2 Runtime to all users at the same time thus we need to ensure that our test suite is kept inline with this update cycle and have no choice about the version that we use.

The error is not limited to version 117 of the edge driver, it seems that there are issues from version 117 onwards. I’ve tested numerous versions of the driver post version 117 to see whether I can resolve the issue, but it seems consistently broken when trying to test a webview. If I test using just a browser then I do not see the issue.

I followed this MS learning doc to prove that the driver works with edge and all the tests were successful -

I also followed the MS learning doc on how to automate tests with edge driver and selenium so our test suite and app were removed from the equation and I see the same ASCIIZ error -

Any help or guidance you can provide will be very much appreciated.



Microsoft Edge
Microsoft Edge
A Microsoft cross-platform web browser that provides privacy, learning, and accessibility tools.
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  1. PhilC 0 Reputation points

    This error has been resolved in the latest 119 release of the of the edge webdriver.

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