Libtorrent 2.1.1 build fails

[alervd]

I'm trying to use the very same build script which I've successfully used to build Libtorrent 2.0.11 for Windows.
Build seems to going fine and it actually builds the static lib. However, at the very end, it outputs weird errors and fails.

Is it a bug? Or maybe something was changed in the build system and I need to adjust my build script accordingly?

[... omitted output ....]
common.copy D:\Work\Source\proj\libtorrent-build\v2_1\windowsx86\lib\libtorrent-rasterbar.lib
bin\msvc-14.3\debug\cxxstd-20-iso\deprecated-functions-off\link-static\logging-off\threading-multi\libtorrent-rasterbar.lib
        1 file(s) copied.
Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libjuice_msvc deps\libdatachannel\bin\juice-static.lib
-- Selecting Windows SDK version 10.0.22621.0 to target Windows 10.0.19045.
-- The C compiler identification is MSVC 19.42.34436.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/2022/Community/VC/Tools/MSVC/14.42.34433/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - not found
-- Found Threads: TRUE
-- Configuring done (8.5s)
-- Generating done (0.1s)
-- Build files have been written to: D:/Work/Source/proj/libtorrent-build/v2_1/libtorrent-x86/deps/libdatachannel/deps/libjuice/build-openssl-debug
MSBuild version 17.12.12+1cce77968 for .NET Framework
Build started 8/14/2026 12:46:46 PM.

Project "D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln" on node 1 (default targets).
D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln.metaproj : error MSB4126: The specified solution configuration "debug|x86" is invalid. Please specify a valid solution configuration using the Configuration and Platform properties (e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU") or leave those properties blank to use the default solution configuration. [D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln]
Done Building Project "D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln" (default targets) -- FAILED.

Build FAILED.

"D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln" (default target) (1) ->
(ValidateSolutionConfiguration target) ->
  D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln.metaproj : error MSB4126: The specified solution configuration "debug|x86" is invalid. Please specify a valid solution configuration using the Configuration and Platform properties (e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU") or leave those properties blank to use the default solution configuration. [D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\libjuice\build-openssl-debug\libjuice.sln]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.05
'cp' is not recognized as an internal or external command,
operable program or batch file.

        SET OLDD=%CD%
    cd D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel/deps/libjuice
    mkdir build-openssl-debug
    cd build-openssl-debug
    cmake -G "Visual Studio 17 2022" -DUSE_NETTLE=0 ..
    msbuild libjuice.sln /property:Configuration=debug
    cd %OLDD%
    cp D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel/deps/libjuice/build-openssl-debug/Release/juice-static.lib deps\libdatachannel\bin\juice-static.lib

...failed Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libjuice_msvc deps\libdatachannel\bin\juice-static.lib...
...skipped <pD:\Work\Source\proj\libtorrent-build\v2_1\windowsx86\lib>juice-static.lib for lack of <pdeps\libdatachannel\bin>juice-static.lib...
Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libusrsctp_msvc deps\libdatachannel\bin\usrsctp.lib
CMake Warning (dev) at CMakeLists.txt:32 (project):
  cmake_minimum_required() should be called prior to this top-level project()
  call.  Please see the cmake-commands(7) manual for usage documentation of
  both commands.
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Selecting Windows SDK version 10.0.22621.0 to target Windows 10.0.19045.
-- The C compiler identification is MSVC 19.42.34436.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/2022/Community/VC/Tools/MSVC/14.42.34433/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- No build type selected, using DEBUG
-- Looking for include file sys/queue.h
-- Looking for include file sys/queue.h - not found
-- Looking for include files sys/socket.h, linux/if_addr.h
-- Looking for include files sys/socket.h, linux/if_addr.h - not found
-- Looking for include files sys/socket.h, linux/rtnetlink.h
-- Looking for include files sys/socket.h, linux/rtnetlink.h - not found
-- Looking for 4 include files sys/types.h, ..., netinet/ip_icmp.h
-- Looking for 4 include files sys/types.h, ..., netinet/ip_icmp.h - not found
-- Looking for 3 include files sys/types.h, ..., net/route.h
-- Looking for 3 include files sys/types.h, ..., net/route.h - not found
-- Looking for include file stdatomic.h
-- Looking for include file stdatomic.h - not found
-- Looking for usrsctp.h
-- Looking for usrsctp.h - found
-- Performing Test have_sa_len
-- Performing Test have_sa_len - Failed
-- Performing Test have_sin_len
-- Performing Test have_sin_len - Failed
-- Performing Test have_sin6_len
-- Performing Test have_sin6_len - Failed
-- Performing Test have_sconn_len
-- Performing Test have_sconn_len - Failed
-- Compiler flags (CMAKE_C_FLAGS): /DWIN32 /D_WINDOWS /W4 /wd4100 /wd4127 /wd4200 /wd4214 /wd4706 /wd4245 /wd4389 /wd4702 /wd4701 /wd4244
-- Performing Test has_wno_address_of_packed_member
-- Performing Test has_wno_address_of_packed_member - Failed
-- Performing Test has_wno_deprecated_declarations
-- Performing Test has_wno_deprecated_declarations - Failed
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - not found
-- Found Threads: TRUE
-- link library: ws2_32
-- Configuring done (15.4s)
-- Generating done (0.1s)
-- Build files have been written to: D:/Work/Source/proj/libtorrent-build/v2_1/libtorrent-x86/deps/libdatachannel/deps/usrsctp/build-debug
MSBuild version 17.12.12+1cce77968 for .NET Framework
Build started 8/14/2026 12:46:52 PM.

Project "D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln" on node 1 (default targets).
D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln.metaproj : error MSB4126: The specified solution configuration "debug|x86" is invalid. Please specify a valid solution configuration using the Configuration and Platform properties (e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU") or leave those properties blank to use the default solution configuration. [D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln]
Done Building Project "D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln" (default targets) -- FAILED.

Build FAILED.

"D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln" (default target) (1) ->
(ValidateSolutionConfiguration target) ->
  D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln.metaproj : error MSB4126: The specified solution configuration "debug|x86" is invalid. Please specify a valid solution configuration using the Configuration and Platform properties (e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU") or leave those properties blank to use the default solution configuration. [D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel\deps\usrsctp\build-debug\usrsctplib.sln]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.04
'cp' is not recognized as an internal or external command,
operable program or batch file.

        SET OLDD=%CD%
    cd D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel/deps/usrsctp
    mkdir build-debug
    cd build-debug
    cmake -G "Visual Studio 17 2022" -Dsctp_werror=0 -Dsctp_build_shared_lib=0 -Dsctp_build_programs=0 -Dsctp_inet=0 -Dsctp_inet6=0 ..
    msbuild usrsctplib.sln /property:Configuration=debug
    cd %OLDD%
    cp D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel/deps/usrsctp/build-debug/usrsctplib/Release/usrsctp.lib deps\libdatachannel\bin\usrsctp.lib

...failed Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libusrsctp_msvc deps\libdatachannel\bin\usrsctp.lib...
...skipped <pD:\Work\Source\proj\libtorrent-build\v2_1\windowsx86\lib>usrsctp.lib for lack of <pdeps\libdatachannel\bin>usrsctp.lib...

...updated 589 targets...

...skipped 2 targets...
   <pD:\Work\Source\proj\libtorrent-build\v2_1\windowsx86\lib>juice-static.lib
   <pD:\Work\Source\proj\libtorrent-build\v2_1\windowsx86\lib>usrsctp.lib

...failed updating 2 targets...
   Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libjuice_msvc deps\libdatachannel\bin\juice-static.lib
   Jamfile<D:\Work\Source\proj\libtorrent-build\v2_1\libtorrent-x86\deps\libdatachannel>.make_libusrsctp_msvc deps\libdatachannel\bin\usrsctp.lib

[arvidn]

claude has this to say:

deps/libdatachannel/Jamfile's make_libjuice_msvc and make_libusrsctp_msvc rules invoke cmake -G "Visual Studio 17 2022" for the vendored libjuice/usrsctp deps without an -A flag. With no explicit architecture, the VS2022 generator defaults to x64. But the user is building the x86 (32-bit) configuration of libtorrent, their build shell has Platform=x86 set (from vcvarsall x86), so when msbuild libjuice.sln /property:Configuration=debug runs with no explicit /property:Platform, MSBuild picks up Platform=x86 from the environment and asks for solution configuration debug|x86. That configuration doesn't exist in the x64-only .sln CMake generated

This sounds similar to a recent fix in to make 32bit builds work on linux. I suppose I don't have any CI coverage of 32bit builds on windows. #8532 (specifically this file: https://github.com/arvidn/libtorrent/pull/8532/changes#diff-f52881b5aaae6b6f907041fbbd8cf2ba9c9d2860a99f8905419b31415b21e53a ).

claude proposes this fix to libdatachannel:

diff --git a/Jamfile b/Jamfile
index 9c740467..447dc7b6 100644
--- a/Jamfile
+++ b/Jamfile
@@ -110,7 +110,12 @@ rule make_libusrsctp_msvc ( targets * : sources * : properties * )
 {
        local VARIANT = [ feature.get-values <variant> : $(properties) ] ;
        VARIANT on $(targets) = $(VARIANT) ;
-       BUILD_DIR on $(targets) = "build-$(VARIANT)" ;
+       local ADDRESS_MODEL = [ feature.get-values <address-model> : $(properties) ] ;
+       local ARCH = "x64" ;
+       if $(ADDRESS_MODEL) = "32"
+       { ARCH = "Win32" ; }
+       ARCH on $(targets) = $(ARCH) ;
+       BUILD_DIR on $(targets) = "build-$(ARCH)-$(VARIANT)" ;
 }
 actions make_libusrsctp_msvc
 {
@@ -118,8 +123,8 @@ actions make_libusrsctp_msvc
     cd $(CWD)/deps/usrsctp
     mkdir $(BUILD_DIR)
     cd $(BUILD_DIR)
-    cmake -G "Visual Studio 17 2022" -Dsctp_werror=0 -Dsctp_build_shared_lib=0 -Dsctp_build_programs=0 -Dsctp_inet=0 -Dsctp_inet6=0 ..
-    msbuild usrsctplib.sln /property:Configuration=$(VARIANT)
+    cmake -G "Visual Studio 17 2022" -A $(ARCH) -Dsctp_werror=0 -Dsctp_build_shared_lib=0 -Dsctp_build_programs=0 -Dsctp_inet=0 -Dsctp_inet6=0 ..
+    msbuild usrsctplib.sln /property:Configuration=$(VARIANT) /property:Platform=$(ARCH)
     cd %OLDD%
     cp $(CWD)/deps/usrsctp/$(BUILD_DIR)/usrsctplib/Release/usrsctp.lib $(<)
 }
@@ -165,14 +170,19 @@ rule make_libjuice_msvc ( targets * : sources * : properties * )
 {
        local VARIANT = [ feature.get-values <variant> : $(properties) ] ;
        VARIANT on $(targets) = $(VARIANT) ;
+       local ADDRESS_MODEL = [ feature.get-values <address-model> : $(properties) ] ;
+       local ARCH = "x64" ;
+       if $(ADDRESS_MODEL) = "32"
+       { ARCH = "Win32" ; }
+       ARCH on $(targets) = $(ARCH) ;
        if <gnutls>on in $(properties)
        {
-               BUILD_DIR on $(targets) += "build-gnutls-$(VARIANT)" ;
+               BUILD_DIR on $(targets) += "build-gnutls-$(ARCH)-$(VARIANT)" ;
                CMAKEOPTS on $(targets) = "-DUSE_NETTLE=1" ;
        }
        else
        {
-               BUILD_DIR on $(targets) += "build-openssl-$(VARIANT)" ;
+               BUILD_DIR on $(targets) += "build-openssl-$(ARCH)-$(VARIANT)" ;
                CMAKEOPTS on $(targets) = "-DUSE_NETTLE=0" ;
        }
 }
@@ -182,8 +192,8 @@ actions make_libjuice_msvc
     cd $(CWD)/deps/libjuice
     mkdir $(BUILD_DIR)
     cd $(BUILD_DIR)
-    cmake -G "Visual Studio 17 2022" $(CMAKEOPTS) ..
-    msbuild libjuice.sln /property:Configuration=$(VARIANT)
+    cmake -G "Visual Studio 17 2022" -A $(ARCH) $(CMAKEOPTS) ..
+    msbuild libjuice.sln /property:Configuration=$(VARIANT) /property:Platform=$(ARCH)
     cd %OLDD%
     cp $(CWD)/deps/libjuice/$(BUILD_DIR)/Release/juice-static.lib $(<)
 }

In an ideal world, the Visual Studio 17 2022 would also depend on which toolset is selected by b2.

@paullouisageneau ping

[arvidn]

actually, I think the problem is that libtorrent CI applies this patch already, and libdatachannel has now been updated with the patch, but the submodule has not been bumped.

So it might actually be enough to bump the submodule

[arvidn]

The fix landed in libdatachannel here: paullouisageneau/libdatachannel#1601

But I don't believe there's been a new release since than, so I can't bump the dependency yet

[alervd]

Thanks.
However, I've managed to revamp my build script to use cmake instead of b2. Seems to build fine now.