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TestComplete crashes on start and the KB4507460 Windows update

TestComplete crashes on start and the KB4507460 Windows update

Dear Friends!


We have identified an unpleasant issue with TestComplete crashing on startup, and it already was reported by several users. The issue starts to occur after one of the latest Microsoft updates for Windows 10 version 1609 (build 14393) is installed - KB4507460. The problem is related to a known bug with the JScript engine and Microsoft has confirmed it. You can find multiple reports of this issue on the Internet:


The issue occurs in Internet Explorer and embedded browsers based on it. Since TestComplete uses the WebBrowser control in multiple places within UI (e.g. Start Page or Test Log), the issue affects our tool as well. We cannot fix the problem without replacing the web rendering engine in TestComplete, so we have to wait until Microsoft fixes the issue.


However, there are a couple of workarounds to the problem that can be applied now. The first one is recommended by Microsoft - enabling the script debugger in the system. You can find details on this workaround in the below article in the Known Issues section:


Here is a quote from this article:

Internet Explorer 11 may fail to render some JavaScript after installing this update. You may also have issues with apps using JavaScript or the WebBrowser control, such as the present PowerPoint feature of Skype Meeting Broadcast.

To mitigate this issue, you need to Enable Script Debugging using one of the following ways.


You can configure the below registry key:

Registry setting: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\Main

Value: Disable Script Debugger

Type: REG_SZ

Data: no


Or you can Enable Script Debugging in Internet Settings. You can open Internet Setting by either typing Internet Settings into the search box on Windows or by selecting Internet Options in Internet Explorer. Once open, select Advanced then Browsing and finally, select Enable Script Debugging.


We are working on a resolution and will provide an update in an upcoming release.


The second workaround is a result of the fact that only the x64 version of the JScript engine is affected. It is possible to use the 32-bit version of TestComplete with which the problem does not occur. This version is installed along with the default 64-bit version and located by this path:

C:\Program Files (x86)\SmartBear\TestComplete 14\Bin\TestComplete.exe


And the final possible solution to this problem is updating your Windows to the latest version that is version 1903 (build 18362).


I hope this information helps! Happy testing!

Dmitry Nikolaev

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