Known issues for browsers in TruClient

This section describes troubleshooting and limitations for browsers in TruClient.


  • When accessing HTTP/2 web pages in Chromium, the replay log displays HTTP/1.1 in the HTTP response header.

  • The Minimum supported secure protocol setting in TruClient General Settings > Browser Settings and VuGen Runtime Settings > Load Section > Browser > SSL is not supported. TruClient Chromium always chooses the most secure protocol supported by both Chromium and the web server under test.

  • Chromium cannot record or replay inside dynamic iframes.

  • Global variable cannot be used in steps in Chromium.

    For example, this does not work:

    Step 1: Evaluate JavaScript code Global.myserver = "";

    Step 2: Navigate to Global.myserver

  • When there are multiple certificates available for use to visit a web page, Chromium can only pick up the first certificate.

  • When recording a script, the top level frame navigation event is omitted due to performance optimization. As a result, the Go Back or Go Forward step is not recorded automatically.

    Resolution: Manually add a Go Back a page or Go Forward a page step.

  • The ''Wait for File Download' step does not support the file types that are treated as dangerous by the browser. The types include but are not limited to .exe, .dll, .msi, .xml, .xsl, .js, .bat, .chm, .cmd, .jar, and .ini. The download of such files is blocked by the following prompt.

    "This type of file can harm your computer. Do you want to keep xxx anyway?"

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TruClient Browser

  • Due to changes in Mozilla technology, TruClient Browser (based on Mozilla Firefox) consumes significantly higher resources than Chromium. As a result, we recommend using the default Chromium browser instead.

  • TruClient Browser can only be used with applications that support the Mozilla Firefox browser.
  • TruClient Browser does not support Kerberos authentication. If the server also supports NTLM, TruClient automatically moves the authentication to NTLM and continues working.
  • Java applets and Silverlight are not supported for TruClient Browser. User actions on UI elements that are based on Java applets and Silverlight technologies are currently not supported for record and replay.

  • TruClient Browser is unable to record and replay actions in dynamic iframe.

    In some AUT pages, some iframes are created dynamically by user actions (for example, by clicking a button). For such iframes, the browser cannot record and replay these actions.

    Resolution: Add the EnableDynamicIframeDetection= setting to the script's default.cfg file (under the "TruClient" section) with one of the following values:

    Value Details
    0 Disables the setting.
    1 Enables the setting when the AUT document is loaded (on the window.onload event).
    2 Enables the setting when the script is loaded to the page.

    Note: Enabling dynamic iframe detection can impact the AUT page’s performance.

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Other limitations

  • It is recommended to avoid making HTTPS connections using TLS 1.0 and TLS 1.1, because they will be disabled by the browsers in the future.
  • Due to dependency on browser vendors, TruClient's footprint might be affected by internal architectural changes to the browsers. In addition, long runs may consume more memory.

    To reduce the overall memory used, we recommend that you enable Simulate a new user for each iteration (found in General Settings > Runtime Settings > Replay).

  • If you get different results for same load test run in different browsers, see End events, run times, and transaction times on different browsers.

  • If you receive the error message: VuGen cannot open the TruClient browser, this error may have occurred because you do not have the proper permissions to establish communication between VuGen and the TruClient browser.

    Recommendation: Ask your administrator or a power user to run this command:

    netsh http add urlacl url=<port_given_in_the_error_message>/ user=<DOMAIN>\<USER_NAME>

    Example: netsh http add urlacl url= user=DOMAIN\john

  • If you receive the error message: VuGen cannot open the TruClient browser because the port range is busy or invalid, this is because a free port is needed to open a server. The server is open on the URL<free_port>/ .

    You can configure the free port in the following xml file:


    <BrowserCommunicationServerEndPort value="8090" />
    <BrowserCommunicationServerStartPort value="8080" />

    The default port range is between 8080 through 8090. If there is a problem with the ports (all ports are busy or the start port is bigger than the end port), you can change the range in the configuration file.

    If you are unable to resolve this issue, contact Software Support.

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See also: