I have this script:

#!/bin/sh
ANAME="RELBASE_""$1"".tar.gz"
cd /tmp
wget "https://repo.palemoon.org/mcp-graveyard/UXP/archive/""$ANAME" -O "$ANAME"
tar -xzf "$ANAME"
rm "$ANAME"
cd uxp
mkdir application
cd application
ANAME="iceweasel-uxp-""$2"".tar.gz"
wget "https://repo.hyperbola.info:50000/other/iceweasel-uxp/""$ANAME" -O "$ANAME"
tar xzf "$ANAME"
rm "$ANAME"
mv "iceweasel-uxp-""$2" iceweasel-uxp
sed -i 's/Vendor=Mozilla/Vendor=Hyperbola/g' iceweasel-uxp/app/application.ini
sed -i 's/Name=Firefox/Name=Iceweasel-UXP/g' iceweasel-uxp/app/application.ini
cd ..
echo 'mk_add_options AUTOCLOBBER=1' >> .mozconfig
echo 'mk_add_options MOZ_MAKE_FLAGS="-j7"' >> .mozconfig
echo 'ac_add_options --enable-application=iceweasel-uxp' >> .mozconfig
echo 'ac_add_options --enable-default-toolkit=cairo-gtk2' >> .mozconfig
echo 'ac_add_options --enable-alsa' >> .mozconfig
echo 'ac_add_options --disable-pulseaudio' >> .mozconfig
echo 'ac_add_options --enable-optimize=-O2' >> .mozconfig
echo 'ac_add_options --enable-strip' >> .mozconfig
echo 'ac_add_options --disable-debug' >> .mozconfig
echo 'ac_add_options --enable-release' >> .mozconfig
echo 'ac_add_options --disable-sync' >> .mozconfig
echo 'ac_add_options --disable-verify-mar' >> .mozconfig
echo 'ac_add_options --disable-updater' >> .mozconfig
echo 'ac_add_options --disable-crashreporter' >> .mozconfig
echo 'ac_add_options --disable-maintenance-service' >> .mozconfig
echo 'ac_add_options --disable-tests' >> .mozconfig
echo 'ac_add_options --disable-ipdl-tests' >> .mozconfig
sed -i "s/die('Cannot find project %s', build_app)/fake = 0/g" build/moz.configure/init.configure
./mach build
./mach package
cp ./obj-x86_64-pc-linux-gnu/dist/iceweasel-uxp-*.tar.bz2 /opt/
cd ..
rm -rf ./uxp
cd /opt
tar -xjvf iceweasel-uxp-*.tar.bz2
mv iceweasel-uxp-*.tar.bz2 /a/UTILDISK/UPGRADE/iceweasel-uxp/

Which i called with these parameters:

./build_stable.sh 20210823 2.9 

And it fails with this message:

 0:12.92 /tmp/uxp/old-configure: 71: /tmp/subscript.5GZHt9: Syntax error: Unterminated quoted string
 0:12.95 DEBUG: <truncated - see config.log for full output>
 0:12.95 DEBUG: configure:10321: checking _GTKCHECK_LIBS
 0:12.95 DEBUG: configure:10362: checking for gio-2.0 >= 2.22
 0:12.95 DEBUG: configure:10369: checking MOZ_GIO_CFLAGS
 0:12.95 DEBUG: configure:10374: checking MOZ_GIO_LIBS
 0:12.95 DEBUG: configure:10449: checking for gconf-2.0 >= 1.2.1 gobject-2.0
 0:12.95 DEBUG: configure:10456: checking MOZ_GCONF_CFLAGS
 0:12.95 DEBUG: configure:10461: checking MOZ_GCONF_LIBS
 0:12.95 DEBUG: configure:10722: checking for dbus-1 >= 0.60
 0:12.95 DEBUG: configure:10729: checking MOZ_DBUS_CFLAGS
 0:12.95 DEBUG: configure:10734: checking MOZ_DBUS_LIBS
 0:12.95 DEBUG: configure:10774: checking for dbus-glib-1 >= 0.60
 0:12.95 DEBUG: configure:10781: checking MOZ_DBUS_GLIB_CFLAGS
 0:12.95 DEBUG: configure:10786: checking MOZ_DBUS_GLIB_LIBS
 0:12.95 DEBUG: configure:10890: /usr/bin/gcc -std=gnu99 -c -flifetime-dse=1  -fno-strict-aliasing -ffunction-sections -fdata-sections -fno-math-errno -msse2 -mfpmath=sse -pthread  conftest.c 1>&5
 0:12.95 DEBUG: configure:11557: checking for alsa
 0:12.95 DEBUG: configure:11564: checking MOZ_ALSA_CFLAGS
 0:12.95 DEBUG: configure:11569: checking MOZ_ALSA_LIBS
 0:12.95 DEBUG: configure:12263: checking for wget
 0:12.95 DEBUG: configure:12672: checking for valid C compiler optimization flags
 0:12.95 DEBUG: configure:12683: /usr/bin/gcc -std=gnu99 -c -flifetime-dse=1  -fno-strict-aliasing -ffunction-sections -fdata-sections -fno-math-errno -msse2 -mfpmath=sse -pthread -O2  conftest.c 1>&5
 0:12.95 ERROR: old-configure failed
 0:12.97 *** Fix above errors and then restart with\
 0:12.97                "/usr/bin/make -f client.mk build"
 0:12.97 client.mk:374: recipe for target 'configure' failed
 0:12.97 make: *** [configure] Error 1
 0:00.18 /usr/bin/make -C . -j7 -s -w package
 0:00.19 make: Entering directory '/tmp/uxp/obj-x86_64-pc-linux-gnu'
 0:00.19 make: *** No rule to make target 'package'.  Stop.
 0:00.19 make: Leaving directory '/tmp/uxp/obj-x86_64-pc-linux-gnu'

OS is Debian 9, compiler is GCC 7.3. All dependencies should be installed, some months ago this script worked.