Python2 error during WebEngine build Qt 5.12.5

Merlino

Hello!

I have an application written with Qt 5.12.5 which use the WebView control. In Linux it works perfectly, in Windows it cannot be built because the WebView cannot be found. I've googled a lot and finally I have understood that is necessary to build the WebEngine.

So I managed to create the build environment with:
-Python 2.7.9
-Bison, Flex
-GPerf
-ActivePerl
-Visual Studio 2017 Community Edition
-Windows 10 SDK

After setting the MVSC vars and the appropriate paths, I have run the command configure -webengine-proprietary-codecs throught the console in the C:\Qt\5.12.5\Src folder.

Then I moved to the qtwebengine subfolder and ran qmake but this message error is appeared:

A suitable version of python2 could not be found.
QtWebEngine will not be built.

I've re-checked all the environment settings, but nothing seems wrong.

Can anybody help me?

Merlino

This is the result of the configure:

C:\Qt\5.12.5\Src>configure -webengine-proprietary-codecs
+ cd qtbase
+ C:\Qt\5.12.5\Src\qtbase\configure.bat -top-level -webengine-proprietary-codecs
Bootstrapping qmake ...

Microsoft (R) Program Maintenance Utility   versione 14.16.27048.0
Copyright (C) Microsoft Corporation. Tutti i diritti riservati.


Selecting Qt Edition.

Type 'c' if you want to use the Commercial Edition.
Type 'o' if you want to use the Open Source Edition.

Which edition of Qt do you want to use? o

This is the Qt Open Source Edition.

You are licensed to use this software under the terms of
the GNU Lesser General Public License (LGPL) version 3
or the GNU General Public License (GPL) version 2.

Type 'L' to view the GNU Lesser General Public License version 3 (LGPLv3).
Type 'G' to view the GNU General Public License version 2 (GPLv2).
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Do you accept the terms of either license? y


Running configuration tests...
Done running configuration tests.

Configure summary:

Build type: win32-msvc (i386, CPU features: sse sse2)
Compiler: msvc 191627048
Configuration: sse2 aesni sse3 ssse3 sse4_1 sse4_2 avx avx2 avx512f avx512bw avx512cd avx512dq avx512er avx512ifma avx512pf avx512vbmi avx512vl compile_examples f16c largefile precompile_header rdrnd shani x86SimdAlways shared debug_and_release release debug build_all c++11 c++14 c++1z concurrent dbus no-pkg-config release_tools stl
Build options:
  Mode ................................... debug and release; default link: debug; optimized tools
  Optimize release build for size ........ no
  Building shared libraries .............. yes
  Using C standard ....................... C89
  Using C++ standard ..................... C++1z
  Using gold linker ...................... no
  Using precompiled headers .............. yes
  Using LTCG ............................. no
  Target compiler supports:
    SSE .................................. SSE2 SSE3 SSSE3 SSE4.1 SSE4.2
    AVX .................................. AVX AVX2
    AVX512 ............................... F ER CD PF DQ BW VL IFMA VBMI
    Other x86 ............................ AES F16C RDRAND SHA
  Build parts ............................ libs examples tools
  App store compliance ................... no
Qt modules and options:
  Qt Concurrent .......................... yes
  Qt D-Bus ............................... yes
  Qt D-Bus directly linked to libdbus .... no
  Qt Gui ................................. yes
  Qt Network ............................. yes
  Qt Sql ................................. yes
  Qt Testlib ............................. yes
  Qt Widgets ............................. yes
  Qt Xml ................................. yes
Support enabled for:
  Using pkg-config ....................... no
  udev ................................... no
  Using system zlib ...................... no
Qt Core:
  DoubleConversion ....................... yes
    Using system DoubleConversion ........ no
  GLib ................................... no
  iconv .................................. no
  ICU .................................... no
  Tracing backend ........................ <none>
  Logging backends:
    journald ............................. no
    syslog ............................... no
    slog2 ................................ no
  Using system PCRE2 ..................... no
Qt Network:
  getifaddrs() ........................... no
  IPv6 ifname ............................ no
  libproxy ............................... no
  OpenSSL ................................ no
    Qt directly linked to OpenSSL ........ no
  OpenSSL 1.1 ............................ no
  DTLS ................................... no
  SCTP ................................... no
  Use system proxies ..................... yes
Qt Gui:
  Accessibility .......................... yes
  FreeType ............................... yes
    Using system FreeType ................ no
  HarfBuzz ............................... yes
    Using system HarfBuzz ................ no
  Fontconfig ............................. no
  Image formats:
    GIF .................................. yes
    ICO .................................. yes
    JPEG ................................. yes
      Using system libjpeg ............... no
    PNG .................................. yes
      Using system libpng ................ no
  EGL .................................... yes
  OpenVG ................................. no
  OpenGL:
    ANGLE ................................ yes
    Combined ANGLE Library ............... no
    Desktop OpenGL ....................... no
    Dynamic OpenGL ....................... no
    OpenGL ES 2.0 ........................ yes
    OpenGL ES 3.0 ........................ no
    OpenGL ES 3.1 ........................ no
    OpenGL ES 3.2 ........................ no
  Vulkan ................................. no
  Session Management ..................... yes
Features used by QPA backends:
  evdev .................................. no
  libinput ............................... no
  INTEGRITY HID .......................... no
  mtdev .................................. no
  tslib .................................. no
  xkbcommon .............................. no
  X11 specific:
    XLib ................................. no
    XCB Xlib ............................. no
    EGL on X11 ........................... no
QPA backends:
  DirectFB ............................... no
  EGLFS .................................. no
  LinuxFB ................................ no
  VNC .................................... no
  Mir client ............................. no
  Windows:
    Direct 2D ............................ yes
    DirectWrite .......................... yes
    DirectWrite 2 ........................ yes
Qt Sql:
  SQL item models ........................ yes
Qt Widgets:
  GTK+ ................................... no
  Styles ................................. Fusion Windows WindowsVista
Qt PrintSupport:
  CUPS ................................... no
Qt Sql Drivers:
  DB2 (IBM) .............................. no
  InterBase .............................. no
  MySql .................................. no
  OCI (Oracle) ........................... no
  ODBC ................................... yes
  PostgreSQL ............................. no
  SQLite2 ................................ no
  SQLite ................................. yes
    Using system provided SQLite ......... no
  TDS (Sybase) ........................... no
Qt Testlib:
  Tester for item models ................. yes
Qt SerialBus:
  Socket CAN ............................. no
  Socket CAN FD .......................... no
Further Image Formats:
  JasPer ................................. no
  MNG .................................... no
  TIFF ................................... yes
    Using system libtiff ................. no
  WEBP ................................... yes
    Using system libwebp ................. no
Qt QML:
  QML network support .................... yes
  QML debugging and profiling support .... yes
  QML sequence object .................... yes
  QML list model ......................... yes
  QML XML http request ................... yes
  QML Locale ............................. yes
  QML delegate model ..................... yes
Qt Quick:
  Direct3D 12 ............................ yes
  AnimatedImage item ..................... yes
  Canvas item ............................ yes
  Support for Qt Quick Designer .......... yes
  Flipable item .......................... yes
  GridView item .......................... yes
  ListView item .......................... yes
  TableView item ......................... yes
  Path support ........................... yes
  PathView item .......................... yes
  Positioner items ....................... yes
  Repeater item .......................... yes
  ShaderEffect item ...................... yes
  Sprite item ............................ yes
Qt Scxml:
  ECMAScript data model for QtScxml ...... yes
Qt Gamepad:
  SDL2 ................................... no
Qt 3D:
  Assimp ................................. yes
  System Assimp .......................... no
  Output Qt3D Job traces ................. no
  Output Qt3D GL traces .................. no
  Use SSE2 instructions .................. no
  Use AVX2 instructions .................. no
  Aspects:
    Render aspect ........................ yes
    Input aspect ......................... yes
    Logic aspect ......................... yes
    Animation aspect ..................... yes
    Extras aspect ........................ yes
Qt 3D Renderers:
  OpenGL Renderer ........................ yes
Qt 3D GeometryLoaders:
  Autodesk FBX ........................... no
Qt Wayland Client ........................ no
Qt Wayland Compositor .................... no
Qt Bluetooth:
  BlueZ .................................. no
  BlueZ Low Energy ....................... no
  Linux Crypto API ....................... no
  WinRT Bluetooth API (desktop & UWP) .... yes
Qt Sensors:
  sensorfw ............................... no
Qt Quick Controls 2:
  Styles ................................. Default Fusion Imagine Material Universal
Qt Quick Templates 2:
  Hover support .......................... yes
  Multi-touch support .................... yes
Qt Positioning:
  Gypsy GPS Daemon ....................... no
  WinRT Geolocation API .................. yes
Qt Location:
  Qt.labs.location experimental QML plugin . yes
  Geoservice plugins:
    OpenStreetMap ........................ yes
    HERE ................................. yes
    Esri ................................. yes
    Mapbox ............................... yes
    MapboxGL ............................. no
    Itemsoverlay ......................... yes
QtXmlPatterns:
  XML schema support ..................... yes
Qt Multimedia:
  ALSA ................................... no
  GStreamer 1.0 .......................... no
  GStreamer 0.10 ......................... no
  Video for Linux ........................ no
  OpenAL ................................. no
  PulseAudio ............................. no
  Resource Policy (libresourceqt5) ....... no
  Windows Audio Services ................. yes
  DirectShow ............................. yes
  Windows Media Foundation ............... yes
  Media player backend ................... DirectShow
Qt Tools:
  QDoc ................................... no
Qt WebEngine:
  Embedded build ......................... no
  Full debug information ................. no
  Pepper Plugins ......................... yes
  Printing and PDF ....................... yes
  Proprietary Codecs ..................... yes
  Spellchecker ........................... yes
  Native Spellchecker .................... no
  WebRTC ................................. yes
  Use System Ninja ....................... no
  Geolocation ............................ yes
  WebChannel support ..................... yes
  Use v8 snapshot ........................ yes
  Kerberos Authentication ................ yes

Note: No wayland-egl support detected. Cross-toolkit compatibility disabled.

WARNING: QDoc will not be compiled, probably because libclang could not be located. This means that you cannot build the Qt documentation.

Either ensure that llvm-config is in your PATH environment variable, or set LLVM_INSTALL_DIR to the location of your llvm installation.
On Linux systems, you may be able to install libclang by installing the libclang-dev or libclang-devel package, depending on your distribution.
On macOS, you can use Homebrew's llvm package.
On Windows, you must set LLVM_INSTALL_DIR to the installation path.

WARNING: Python version 2 (2.7.5 or later) is required to build QtWebEngine.

Qt is now configured for building. Just run 'nmake'.
Once everything is built, you must run 'nmake install'.
Qt will be installed into 'C:\Qt\Qt-5.12.5'.

Prior to reconfiguration, make sure you remove any leftovers from
the previous build.

jsulm

@Merlino Maybe you can find more information in config.log file?

Merlino

@jsulm the config.log contains this error:

loaded result for config test config.qtwebengine_core.tests.webengine-python2
'python2.exe' not found in PATH. Checking for 'python.exe'.
Unsupported python version: ...
A suitable Python 2 executable could not be located.

But python2.exe is in the path:

jsulm

@Merlino It looks to me like the configure script ignores PATH (I assume the Python bin folder is there).
Check whether configure has some parameters to specify Python location (configure -h).

What I noticed: to build Qt modules you should use the MSVC terminal which initialises the environment.

Merlino

@jsulm Thank you for your answer, I've checked the configure switches and I have found:

configure -recheck-all

After this the Python2.exe has been correctly recognized.

jsulm

@Merlino Did you run configure at least once before installing Python? That could explain the problem - I think configure caches its findings.

Merlino

@jsulm Yes I did, but the first time I suppose that in the PATH variable the Python2 path was after the Python3 path, so the configure did not find it.