Re: Need help with postgresql build on windows

Hi Nazir,

My problem got resolved after using the flex bison from the link you
provided. Thank you so much!

Thanks and Regards,
Prafulla

On Mon, Jan 5, 2026 at 12:54 PM Prafulla Ranadive <pprandive(dot)pgsql(at)gmail(dot)com>
wrote:

> Hi Nazir,
>
> Thank you for your email. Sure, I will try using flex bison from link
> shared by you.
> I have stepped out for some personal work so I will be able to try out
> only after 4 hours from now.
> I will let you know as soon as I try that out. Once again thank you so
> much.
>
> Regards,
> Prafulla
>
> On Mon, 5 Jan, 2026, 12:09 pm Nazir Bilal Yavuz, <byavuz81(at)gmail(dot)com>
> wrote:
>
>> Hi,
>>
>> On Mon, 5 Jan 2026 at 08:28, Prafulla Ranadive
>> <pprandive(dot)pgsql(at)gmail(dot)com> wrote:
>> >
>> > Hello,
>> >
>> > I have started exploring Postgresql recently.
>> > I am trying to build Postgresql from source on a windows machine. I am
>> referring to the page
>> https://www.postgresql.org/docs/current/install-meson.html#INSTALL-SHORT-MESON
>> >
>> > The ninja command is failing with the error message:
>> >
>> > PS C:\PostgreSQLworkspace\postgres\build> ninja
>> > [142/2102] Generating src/fe_utils/psqlscan with a custom command
>> > FAILED: src/fe_utils/psqlscan.c
>> > "C:\MyPrograms\Meson\meson.exe" "runpython" "../src/tools/pgflex"
>> "--builddir" "." "--srcdir" ".." "--privatedir" "src/fe_utils/psqlscan.c.p"
>> "--flex" "C:\MyPrograms\GnuWin32\bin\flex.EXE" "--perl"
>> "C:\Strawberry\perl\bin\perl.EXE" "-i" "../src/fe_utils/psqlscan.l" "-o"
>> "src/fe_utils/psqlscan.c" "--no-backup" "--" "-Cfe" "-p" "-p"
>> > C:\MyPrograms\GnuWin32\bin\flex.EXE: can't open
>> C:\PostgreSQLworkspace\postgres\build\src\fe_utils\psqlscan.c
>> > [146/2102] Generating src/backend/bootstrap/bootscanner with a custom
>> command
>> > FAILED: src/backend/bootstrap/bootscanner.c
>> > "C:\MyPrograms\Meson\meson.exe" "runpython" "../src/tools/pgflex"
>> "--builddir" "." "--srcdir" ".." "--privatedir"
>> "src/backend/bootstrap/bootscanner.c.p" "--flex"
>> "C:\MyPrograms\GnuWin32\bin\flex.EXE" "--perl"
>> "C:\Strawberry\perl\bin\perl.EXE" "-i"
>> "../src/backend/bootstrap/bootscanner.l" "-o"
>> "src/backend/bootstrap/bootscanner.c"
>> > C:\MyPrograms\GnuWin32\bin\flex.EXE: can't open
>> C:\PostgreSQLworkspace\postgres\build\src\backend\bootstrap\bootscanner.c
>> > [147/2102] Generating src/backend/parser/scan with a custom command
>> > FAILED: src/backend/parser/scan.c
>> > "C:\MyPrograms\Meson\meson.exe" "runpython" "../src/tools/pgflex"
>> "--builddir" "." "--srcdir" ".." "--privatedir"
>> "src/backend/parser/scan.c.p" "--flex"
>> "C:\MyPrograms\GnuWin32\bin\flex.EXE" "--perl"
>> "C:\Strawberry\perl\bin\perl.EXE" "-i" "../src/backend/parser/scan.l" "-o"
>> "src/backend/parser/scan.c" "--no-backup" "--" "-CF" "-p" "-p"
>> > C:\MyPrograms\GnuWin32\bin\flex.EXE: can't open
>> C:\PostgreSQLworkspace\postgres\build\src\backend\parser\scan.c
>> > ninja: build stopped: subcommand failed.
>> > PS C:\PostgreSQLworkspace\postgres\build>
>> >
>> > I have enabled full permission on the folder but still no luck.
>> >
>> > Can someone please help me with this? Any troubleshooting pointers
>> would be a great help!
>>
>> Could you let me know where you downloaded flex from? I am wondering
>> whether it might be this:
>> https://gnuwin32.sourceforge.net/packages/flex.htm.
>>
>> For our Windows CI, we use flex and bison from this release instead:
>> https://github.com/lexxmark/winflexbison/releases/tag/v2.5.24.
>>
>> If you have a chance, would you mind trying flex and bison from that
>> source to see if it helps?
>>
>> --
>> Regards,
>> Nazir Bilal Yavuz
>> Microsoft
>>
>