Unable to install "Developer's System CE" package with OpenTap 9.17.3

Installed OpenTAP 9.17.3 (with the “Download for Windows” link). I then attempted to install “Developer’s System CE” as per the Windows installation instructions. The package install aborted with an unfound assembly reference to “OpenTap, Version=, …”, which is not the version I have installed. It looks like the reference to OpenTap is from Keysight.OpenTap.Wpf.dll (part of the Developer’s System CE package). I used dotPeak to inspect Keysight.OpenTap.Wpf.dll and it does have references to the version of the various OpenTap assemblies.

BTW, the “Download OpenTAP … here” link on the “Getting Started | OpenTAP” page is broken.


@michael_hall Welcome!

With 9.17 we migrated to .NET 6, which was a pretty substantial change. There are still a few loose ends that are being fixed in a patch release in the next few days.

If you want to get a new install of Community Edition right now, I would recommend using version 9.16 of OpenTAP. Or if you are able to wait a day or two you should be able to have the latest.

Hi @michael_hall , thanks for reaching out!

The dead links have been fixed, thanks for the heads up.

The installation error you mentioned has been fixed and will be included in the next patch release which is scheduled later today (OpenTAP version 9.17.4 and Developer’s System CE version 9.17.2)

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When will we have a installer for download at the opentap.io ?

The installer will be available shortly! The new version is already available on the repository.

If you need the installer immediately it can be downloaded from the GitHub pipeline: https://github.com/opentap/opentap/suites/5750058245/artifacts/190927671


@michael_hall @tch11 9.17.4 is now on Downloads | OpenTAP

Still an install problem with OpenTAP 9.17.4. The “Results View CE” package fails to install (when trying to install the “Developer’s System CE” package). The “Results View CE” package is trying to install the contained “Editor CE” dependent package which contains “Keysight.OpenTap.CommunityEditionPopup.dll”. The “Keysight.OpenTap.CommunityEditionPopup” assembly has a dependency upon “Keysight.OpenTap.Wpf” version, but the installed version of “Keysight.OpenTap.Wpf” is

Hi @michael_hall,

Can you explain how you are installing Developer’s System CE?

For me it installs correctly if I follow the Getting Started guide.

Rolf, you had the TAP_PATH environment variable set before running the installer. This masks the installer problems. I described this issue in the “Install OpenTAP” step 9 below.

To illustrate the problems, it is necessary to Uninstall the existing OpenTAP install before installing the new OpenTAP version.

Uninstall / Clean-up OpenTAP install:

  1. This “Uninstall” procedure assumes you have a previous version of OpenTAP installed.

  2. In “Apps > Apps & features” dialog, select “OpenTAP 9” and select “Uninstall”. In the uninstaller, select the “Completely remove” check box and then complete the “Uninstall”.

  3. Reboot (just to make sure any pending uninstall actions are performed).

  4. BUGS:
    a) “%ProgramFiles%\OpenTAP” diretory still has some files in it (including tap.exe). The “complete” uninstall should completely remove all of the OpenTAP files.

    b) “%LOCALAPPDATA%\OpenTap” directory still has cached OpenTAP packages in it. The “complete” uninstall should remove these cached OpenTAP packages.

    c) In “System > Advanced system settings > Environment Variables…” dialog, notice that the “System variables” still contains a “TAP_PATH” environment variable. The “complete” uninstall should delete the “TAP_PATH” environment variable.

  5. To get back to a “complete” uninstall state, manually remove the “%ProgramFiles%\OpenTAP” & “%LOCALAPPDATA%\OpenTap” directories and delete the “TAP_PATH” environment variable.

  6. Reboot (to make sure “TAP_PATH” is not in any session’s environment).

Install OpenTAP:

  1. In your web browser (e.g. Chrome), go to “opentap.io” and select “Downloads”.

  2. For Windows 10 (or later), select “Download for Windows” (Step 1 in installation guide).

  3. In your web browser (which is still on the “Downloads” page), select the “Windows” Installation Guide.

  4. Run the downloaded “OpenTAP9.17.4.exe”, use all the default settings, and “Install” (Step 2 in installation guide).

  5. Follow the installation guide instructions to install the “Developer’s System CE” package. Open a “Command Prompt” window and type:

    cd %TAP_PATH%

    BUG: the TAP_PATH environment variable is not set by the installer.

  6. Manually “cd” to the OpenTAP installation directory and try to install the package again:

    cd %ProgramFiles%\OpenTAP
    tap package install “Developer’s System CE” -y

    BUG: Installer error “Failed to run install step ‘tap.exe path register’”. This is caused by the OpenTap.OSIntegration.Windows assembly (which implements the “path register” command) having references to versions for OpenTap and OpenTap.Package assemblies when version of the assemblies are installed in this version of OpenTAP.

  7. Let’s work around this installation problem by manually creating the TAP_PATH system environment variable to point to “C:\Program Files\OpenTAP”.

  8. Close the “Command Prompt” window and re-open it (to get the new environment variable created in the previous step.

  9. Repeat the install of the “Developer’s System CE” package. Since the environment variable is set, the “tap path register” install step is bypassed.

    cd %TAP_PATH%
    tap package install “Developer’s System CE” -y

    BUG: While installing “PackageCache\Results Viewer CE.9.17.2+c3ded42f.x64.TapPackage” the package installer is “Starting install step ‘tap.exe communityeditionpopup’”. The Keysight.OpenTap.CommunityEditionPopup ( assembly has a reference to Keysight.OpenTap.Wpf ( assembly, but the version of Keysight.OpenTap.Wpf assembly in the “Packages\WPF Controls” directory is
    If you have a tool like “dotPeak” installed, then when this happens, doPeak starts and you can see the incorrect reference. The output on the command prompt window shows no indication of this error.

  10. If you type “tap communityeditionpopup” at the command prompt, there is a “CliAction” exception message shown.
    If you type “Editor” for the OpenTAP editor, the application window briefly shows and then exits. If you now look at the latest SessionLog, you will see an “Error” line that says “Unable to show EULA dialog” (i.e. not able to load the “Keysight.OpenTap.CommunityEditionPopup” because of the incorrect assembly references noted above.

REQUEST: Most Windows application installers create “Start” menu shortcuts to GUI-based applications (i.e. OpenTap “Editor”, “PackageManager”, “ResultsViewer”, and “RunExplorer”).

Mike Hall (Keysight Retiree, KMF project).
Hi Rolf, Asger, and Brennen.


Thanks for the additional details. The bugs causing the installation to fail have been resolved and will be included in a patch release tomorrow.

%TAP_PATH% is deprecated and is only set for backwards compatibility. I agree that it is a bit weird that files are left over from “complete” uninstalls. This is definitely not intended.

The reason we don’t clear %LOCALAPPDATA%\OpenTap is because there could be other installations that we don’t know about. OpenTAP is intended to be self-contained in the sense that it doesn’t depend on any files outside of the installation folder.

As a sidenote, the dependency on WPF Controls is expected. We update the assembly versions of DLLs during the packaging stage. is the development version of the DLL. The version mismatch occurs because many of the “Developer’s System” packages are built in the same solution. The version mismatch is not the issue because OpenTAP uses a custom assembly resolver. The issue is that the assembly resolver was not properly initialized due to another bug which has since been resolved.

Thanks again for the feedback

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@michael_hall nice to hear from you again! And thanks for the details on these issues. There is now a 9.17.3 version of Developer System CE that should resolve everything above.