Build QT 6.8 for Ubuntu 20.04 ERROR

[MHermann]

Hi all,
I try to build Qt6.8 for Ubuntu 20.04.
I already got several errors and fixed them by installing different things.
But now the build again stops with an error.
But I don't know how to fix it.
Can someone help me?

This is the output:

cmake --build . --parallel 8
[1/1707] Check QtWebEngine support
QtWebEngine will not be built: Build requires nss >= 3.26.
[6/1707] Building CXX object qtopcua/src/opcua/CMakeFiles/OpcUa.dir/x509/qopcuax509certificatesigningrequest_openssl.cpp.o
FAILED: qtopcua/src/opcua/CMakeFiles/OpcUa.dir/x509/qopcuax509certificatesigningrequest_openssl.cpp.o 
/usr/bin/c++ -DOpcUa_EXPORTS -DQT_ASCII_CAST_WARNINGS -DQT_BUILDING_QT -DQT_BUILD_OPCUA_LIB -DQT_CORE_LIB -DQT_DEPRECATED_WARNINGS -DQT_EXPLICIT_QFILE_CONSTRUCTION_FROM_PATH -DQT_LEAN_HEADERS=1 -DQT_MOC_COMPAT -DQT_NETWORK_LIB -DQT_NO_AS_CONST=1 -DQT_NO_CAST_TO_ASCII -DQT_NO_CONTEXTLESS_CONNECT=1 -DQT_NO_DEBUG -DQT_NO_EXCEPTIONS -DQT_NO_FOREACH -DQT_NO_FOREACH=1 -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_NO_QASCONST -DQT_NO_QEXCHANGE -DQT_USE_QSTRINGBUILDER -D_GLIBCXX_ASSERTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I/home/user/qt-hostbuild/qtopcua/src/opcua/OpcUa_autogen/include -I/home/user/qt-hostbuild/qtbase/include -I/home/user/qt-hostbuild/qtbase/include/QtOpcUa -I/home/user/qt5/qtopcua/src/opcua -I/home/user/qt-hostbuild/qtopcua/src/opcua -I/home/user/qt-hostbuild/qtbase/include/QtOpcUa/6.8.0 -I/home/user/qt-hostbuild/qtbase/include/QtOpcUa/6.8.0/QtOpcUa -I/home/user/qt-hostbuild/qtbase/include/QtCore -I/home/user/qt5/qtbase/mkspecs/linux-g++ -I/home/user/qt-hostbuild/qtbase/include/QtNetwork -I/home/user/qt-hostbuild/qtbase/src/corelib -I/home/user/qt-hostbuild/qtbase/include/QtCore/6.8.0 -I/home/user/qt-hostbuild/qtbase/include/QtCore/6.8.0/QtCore -I/home/user/qt-hostbuild/qtbase/src/network -I/home/user/qt-hostbuild/qtbase/include/QtNetwork/6.8.0 -I/home/user/qt-hostbuild/qtbase/include/QtNetwork/6.8.0/QtNetwork -DNDEBUG -O2 -std=c++17 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -fno-exceptions -fconstexpr-ops-limit=40000000 -fPIC -U_FORTIFY_SOURCE -Wsuggest-override -fcf-protection=full -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstack-clash-protection -Winvalid-pch -include /home/user/qt-hostbuild/qtopcua/src/opcua/CMakeFiles/OpcUa.dir/cmake_pch.hxx -MD -MT qtopcua/src/opcua/CMakeFiles/OpcUa.dir/x509/qopcuax509certificatesigningrequest_openssl.cpp.o -MF qtopcua/src/opcua/CMakeFiles/OpcUa.dir/x509/qopcuax509certificatesigningrequest_openssl.cpp.o.d -o qtopcua/src/opcua/CMakeFiles/OpcUa.dir/x509/qopcuax509certificatesigningrequest_openssl.cpp.o -c /home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp
In file included from /home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp:5:
/home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp: In member function ‘QByteArray QOpcUaX509CertificateSigningRequestPrivate::createSelfSignedCertificate(const QOpcUaKeyPair&, int)’:
/home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp:426:34: error: cannot convert ‘GENERAL_NAMES*’ {aka ‘stack_st_GENERAL_NAME*’} to ‘OPENSSL_STACK*’ {aka ‘stack_st*’}
  426 |     q_sk_GENERAL_NAME_push(akid->issuer, generalName);
/home/user/qt5/qtopcua/src/opcua/x509/openssl_symbols_p.h:433:60: note: in definition of macro ‘q_sk_GENERAL_NAME_push’
  433 | #define q_sk_GENERAL_NAME_push(st, val) q_OPENSSL_sk_push((st), (val))
      |                                                            ^~
In file included from /home/user/qt5/qtopcua/src/opcua/x509/openssl_symbols_p.h:211,
                 from /home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp:5:
/home/user/qt5/qtopcua/src/opcua/x509/qsslsocket_openssl11_symbols_p.h:60:57: note:   initializing argument 1 of ‘void q_OPENSSL_sk_push(OPENSSL_STACK*, void*)’
   60 | Q_AUTOTEST_EXPORT void q_OPENSSL_sk_push(OPENSSL_STACK *st, void *data);
      |                                          ~~~~~~~~~~~~~~~^~
In file included from /usr/local/include/openssl/crypto.h:34,
                 from /usr/local/include/openssl/bio.h:30,
                 from /usr/local/include/openssl/asn1.h:30,
                 from /home/user/qt5/qtopcua/src/opcua/x509/openssl_symbols_p.h:23,
                 from /home/user/qt5/qtopcua/src/opcua/x509/qopcuax509certificatesigningrequest_openssl.cpp:5:
/usr/local/include/openssl/x509v3.h:230:1: note: class type ‘GENERAL_NAMES’ {aka ‘stack_st_GENERAL_NAME’} is incomplete
  230 | SKM_DEFINE_STACK_OF_INTERNAL(GENERAL_NAME, GENERAL_NAME, GENERAL_NAME)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
[13/1707] Run gn for target Pdf in /home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64
-- Found Gn: /home/user/qt-hostbuild/qtwebengine/install/bin/gn (found suitable exact version "6.8.0.qtwebengine.qt.io")
-- Running gn in /home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64
-- GN command:
/home/user/qt-hostbuild/qtwebengine/install/bin/gn gen /home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64 --script-executable=/usr/bin/python3 --root=/home/user/qt5/qtwebengine/src/3rdparty/chromium
-- GN arg file:
/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64/args.gn
-- GN args: 
angle_enable_swiftshader=false
blink_symbol_level=0
build_dawn_tests=false
chrome_pgo_phase=0
custom_toolchain="/home/user/qt-hostbuild/qtwebengine/src/pdf/target_toolchain:target"
dawn_use_swiftshader=false
dcheck_always_on=false
enable_arcore=false
enable_ipc_fuzzer=false
enable_precompiled_headers=false
enable_remoting=false
enable_resource_allowlist_generation=false
enable_rust=false
enable_swiftshader=false
enable_swiftshader_vulkan=false
enable_vr=false
enable_web_speech=false
forbid_non_component_debug_builds=false
host_cpu="x64"
host_pkg_config="/usr/bin/pkg-config"
host_toolchain="/home/user/qt-hostbuild/qtwebengine/src/pdf/host_toolchain:host"
init_stack_vars=false
is_cfi=false
is_clang=false
is_component_build=false
is_debug=false
is_gcc=true
is_mingw=false
is_msvc=false
is_official_build=true
is_qtwebengine=true
is_shared=true
is_unsafe_developer_build=false
jumbo_build_excluded=["browser"]
jumbo_file_merge_limit=8
ozone_auto_platforms=false
pdf_enable_v8=false
pdf_enable_xfa=false
pdf_enable_xfa_bmp=false
pdf_enable_xfa_gif=false
pdf_enable_xfa_png=false
pdf_enable_xfa_tiff=false
pdfium_use_qt_libpng=false
pdfium_use_system_libpng=true
pdfium_use_system_libtiff=false
pdfium_use_system_zlib=true
pkg_config="/usr/bin/pkg-config"
qt_freetype_config="/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64:qt_freetype_config"
qt_harfbuzz_config="/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64:qt_harfbuzz_config"
qt_libjpeg_config="/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64:qt_libjpeg_config"
qt_libpng_config="/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64:qt_libpng_config"
qtwebengine_target="/home/user/qt-hostbuild/qtwebengine/src/pdf/Release/x86_64:QtPdf"
strip_absolute_paths_from_debug_symbols=false
symbol_level=0
treat_warnings_as_errors=false
use_allocator_shim=false
use_custom_libcxx=false
use_dawn=false
use_gold=false
use_jumbo_build=true
use_lld=false
use_ml_inliner=false
use_partition_alloc=true
use_partition_alloc_as_malloc=false
use_perfetto_client_library=false
use_qt_freetype=false
use_qt_harfbuzz=false
use_qt_libjpeg=false
use_sysroot=false
use_system_icu=false
use_system_libopenjpeg2=false
use_system_libpng=true
use_system_zlib=true
use_thin_lto=false
v8_enable_webassembly=false
v8_symbol_level=0
-- GN Done. Made 19435 targets from 3157 files in 18328ms
ninja: build stopped: subcommand failed.

[Christian Ehrlicher]

There is no Qt8. 6 - you seem to be compiling some Qt5 version but did not install openssl 1.1 but 3.x development package. Qt5 needs openssl 1.1.

[MHermann]

The folder is named "qt5" but I am building Qt6.8.
It's because in the manual was also the folder name "qt5" used...

And I just installed openssl 3.3.1, because it was complaining about openssl 1.1.

[MHermann]

Any more ideas what could be the problem?

[Christian Ehrlicher]

see https://bugreports.qt.io/browse/QTBUG-122728
Which (and why) Qt6.8 version do you try to build - make sure you're using the latest beta.

[MHermann]

I did:

git clone "https://codereview.qt-project.org/qt/qt5"

And then:

git checkout 6.8

So I hope I am trying to build Qt6.8.0 beta.
Can I check this?
And I try to build this, because I wanted to use the newest version.
Actually I am using Qt5.12.7. And I think it's a little bit outdatet.

[Christian Ehrlicher]

Why don't you simply install a pre-compiled Qt version with the Qt installer instead?

[MHermann]

Because after compiling the Qt version for my host (Ubunut 20.04) I would like to cross-compile it for Raspberry Pi.

[artwaw]

@MHermann You can install soures from the installer and then crosscompile? Still no need for compiling for Ubuntu?

[jarle]

Why such an old Ubuntu?

Just looking briefly at the error my guess is that QT 6.8 code expects a newer openssl library than what's available on your machine. I compiled the latest QT 6.8 branch on Ubuntu 24.04 today without any compilation errors.