14.11. Specific OS notes

14.11.1. CamCOPS client won’t run under Windows Server

Under Windows, server, MF.dll is reported as missing.

What follows assumes 64-bit CamCOPS under 64-bit Windows.

This error can appear under e.g. Windows Server 2008 R2 64-bit (Windows 6.1.7601), when the CamCOPS client is launched. This component is part of “normal” desktop Windows, but not Windows Server (https://serverfault.com/questions/562362/program-missing-dlls). Download and install the Windows Media Services 2008 for Windows Server 2008 R2 package from https://www.microsoft.com/en-gb/download/details.aspx?id=20424. (See also https://support.microsoft.com/en-ca/help/963697/how-to-install-windows-media-services-for-windows-server-2008-r2; potentially relevant.)

The trouble is that this creates thousands of directories within C:\Windows\winsxs, each with a single file in, so (for example) MF.DLL and MFPlat.DLL are in separate directories.

So, copy the most recent OS-relevant version of the following into C:\Windows\system32:

  • MF.DLL

  • MFPlat.DLL


  • MFReadWrite.DLL

  • api-ms-win-core-winrt-l1-1-0.dll.DLLstuck; missing

For example, from an administrative command prompt:

cd c:\windows\system32
copy C:\Windows\winsxs\amd64_microsoft-windows-mediafoundation_31bf3856ad364e35_6.1.7601.24146_none_faf014703c95b62f\mf.dll .
copy C:\Windows\winsxs\amd64_microsoft-windows-mfplat_31bf3856ad364e35_6.1.7601.23471_none_5516292583660fc2\mfplat.dll .
copy C:\Windows\winsxs\amd64_microsoft-windows-enhancedvideorenderer_31bf3856ad364e35_6.1.7601.23471_none_ee0e0e23fc773db4\evr.dll .
copy C:\Windows\winsxs\amd64_microsoft-windows-mfreadwrite_31bf3856ad364e35_6.1.7601.17514_none_177bed732ea3f85f\mfreadwrite.dll .


Not yet fixed.

Decision: Windows Server is an unsuitable OS for the CamCOPS client. (It should be fine for the CamCOPS server!) Use a client edition of Windows for the CamCOPS client.

14.11.2. Setting up an iMac for CamCOPS development


Avoid using a Mac Mini; they are too weedy (e.g. a 2012 model: 2.5 GHz dual-core Intel Core i5, 4 GB RAM, 500 Gb HD) and compiling Qt takes ages. Our 2019 development machine is an iMac 21.5”, 3.2 GHz 6-core (12-thread) Intel Core i7-8700, 32 GB RAM, 1 TB SSD; that’s fine.

  • General computer setup. This includes picking an Apple ID (generally) as well as creating a user.

  • Download and install the open-source edition of Qt. This gets you Qt Creator. You’ll need to log in with your Qt account.

    • Installing Qt triggers installation part of Xcode, if it wasn’t already installed. But not all.

    • Maybe include also the Qt Installer Framework.

    • To make it show up in Launchpad, create a symlink to ~/Qt/Qt Creator.app in /Applications, e.g. with ln -s ~/Qt/Qt\ Creator.app/ /Applications/Qt\ Creator.

  • Install Xcode in full from the App Store. Run it, agree to conditions. Installing Xcode automatically installs the iOS SDK.

  • Download and install Git.

    • Since this is a third-party app, you need to enable installation first, or when it complains. Apple icon [top left] ‣ System Preferences ‣ Security & Privacy ‣ General ‣ Allow apps downloaded from…

  • Fire up a terminal and clone the Git repository (e.g. to ~/camcops/).

  • Download and install Python 3 (MacOS comes with Python 2).

  • Make and activate a Python 3 virtual environment (e.g. in ~/dev/venvs/camcops/).

  • Save some time and effort in the future with a script like this:

    #!/usr/bin/env bash
    export CAMCOPS_SOURCE_DIR=~/camcops
    export CAMCOPS_VENV=~/dev/venvs/camcops
    export CAMCOPS_QT6_BASE_DIR=~/dev/qt_local_build
    . ${CAMCOPS_VENV}/bin/activate
  • However, this won’t affect environment variables for GUI applications. So to get Qt Creator to see the environment variable:

    • see https://superuser.com/questions/476752/setting-environment-variables-in-os-x-for-gui-applications

    • edit ~/Qt/Qt Creator.app/Contents/Info.plist and add a section like:

    • force a refresh by doing this:

      /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user
      killall Finder
  • Same some time and effort by executing pip install -e . from the $CAMCOPS_SOURCE_DIR/server directory. This installs all the Python dependencies for the CamCOPS server, which is overkill, but includes packages used by the build_qt.py script.

  • Install Homebrew.

  • Run ${CAMCOPS_SOURCE_DIR}/tablet_qt/tools/build_qt.py --build_all and every time it stops and says there’s an OS command missing, follow its suggestion.