For me, make buildworld breaks on missing yacc.h. A very similar issue was reported Mar 2, 2016, which was then fixed by r296324 (see: https://lists.freebsd.org/pipermail/freebsd-current/2016-March/059946.html). # uname -a FreeBSD home 11.1-STABLE FreeBSD 11.1-STABLE #1 r329516: Sun Feb 18 15:10:03 CET 2018 me at home:/usr/obj/usr/src/sys/BUFFALO amd64 # svn info Path: . Working Copy Root Path: /usr/src URL: svn://svn.freebsd.org/base/stable/11 Relative URL: ^/stable/11 Repository Root: svn://svn.freebsd.org/base Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f Revision: 345532 Node Kind: directory Schedule: normal Last Changed Author: hselasky Last Changed Rev: 345532 Last Changed Date: 2019-03-26 14:35:23 +0100 (Tue, 26 Mar 2019) Command was a plain # make buildworld (?) ===> usr.bin/mkesdb_static (obj,build-tools) Building /usr/obj/usr/src/usr.bin/mkesdb_static/lex.o /usr/src/usr.bin/mkesdb/lex.l:46:10: fatal error: 'yacc.h' file not found #include "yacc.h" ^~~~~~~~ 1 error generated. *** Error code 1 Stop. make[3]: stopped in /usr/src/usr.bin/mkesdb_static .ERROR_TARGET='lex.o' .ERROR_META_FILE='/usr/obj/usr/src/usr.bin/mkesdb_static/lex.o.meta' .MAKE.LEVEL='3' MAKEFILE='' .MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose' _ERROR_CMD='cc -O2 -pipe -I/usr/src/usr.bin/mkesdb_static -I/usr/src/usr.bin/mke sdb_static/../mkesdb -I/usr/src/usr.bin/mkesdb_static/../../lib/libc/iconv -g -std=gnu99 -Qunused-arguments -I/usr/obj/usr/src/tmp/legacy/usr/include -c lex .c -o lex.o; ;' .CURDIR='/usr/src/usr.bin/mkesdb_static' .MAKE='make' .OBJDIR='/usr/obj/usr/src/usr.bin/mkesdb_static' .TARGETS='build-tools' DESTDIR='' LD_LIBRARY_PATH='' MACHINE='amd64' MACHINE_ARCH='amd64' MAKEOBJDIRPREFIX='/usr/obj' MAKESYSPATH='/usr/src/share/mk' MAKE_VERSION='20170720' PATH='/usr/obj/usr/src/tmp/legacy/usr/sbin:/usr/obj/usr/src/tmp/legacy/usr/bin:/usr/obj/usr/src/tmp/legacy/bin:/sbin:/bin:/usr/sbin:/usr/bin' SRCTOP='/usr/src' OBJTOP='/usr/obj/usr/src' .MAKE.MAKEFILES='/usr/src/share/mk/sys.mk /usr/src/share/mk/local.sys.env.mk /us r/src/share/mk/src.sys.env.mk /etc/src-env.conf /usr/src/share/mk/bsd.mkopt.mk / etc/make.conf /usr/src/share/mk/local.sys.mk /usr/src/share/mk/src.sys.mk /usr/s rc/usr.bin/mkesdb_static/Makefile /usr/src/usr.bin/mkesdb/Makefile.inc /usr/src/ tools/build/mk/bsd.prog.mk /usr/src/share/mk/bsd.prog.mk /usr/src/share/mk/bsd.i nit.mk /usr/src/share/mk/bsd.opts.mk /usr/src/share/mk/bsd.cpu.mk /usr/src/share /mk/local.init.mk /usr/src/share/mk/src.init.mk /usr/src/usr.bin/mkesdb_static/. ./Makefile.inc /usr/src/share/mk/bsd.own.mk /usr/src/share/mk/bsd.compiler.mk /u sr/src/share/mk/bsd.linker.mk /usr/src/share/mk/bsd.libnames.mk /usr/src/share/m k/src.libnames.mk /usr/src/share/mk/src.opts.mk /usr/src/share/mk/bsd.nls.mk /us r/src/share/mk/bsd.confs.mk /usr/src/share/mk/bsd.files.mk /usr/src/share/mk/bsd .incs.mk /usr/src/share/mk/bsd.links.mk /usr/src/share/mk/bsd.man.mk /usr/src/sh are/mk/bsd.dep.mk /usr/src/share/mk/bsd.clang-analyze.mk /usr/src/share/mk/bsd.o bj.mk /usr/src/share/mk/bsd.subdir.mk /usr/src/share/mk/bsd.sys.mk /usr/src/tool s/build/mk/Makefile.boot' .PATH='. /usr/src/usr.bin/mkesdb_static /usr/src/lib/libc/iconv /usr/src/usr.bin /mkesdb' *** Error code 1 Stop. make[2]: stopped in /usr/src .ERROR_TARGET='build-tools_usr.bin/mkesdb_static' .ERROR_META_FILE='' .MAKE.LEVEL='2' MAKEFILE='' .MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose' _ERROR_CMD='.PHONY' .CURDIR='/usr/src' .MAKE='make' .OBJDIR='/usr/obj/usr/src' .TARGETS='build-tools' DESTDIR='' LD_LIBRARY_PATH='' MACHINE='amd64' Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll find there is no forest.