Server response: Error: Impossible package selection

Error building the firmware image
Server response: Error: Impossible package selection

Please report the error message and request
Request Data:

{
"url": "https://sysupgrade.openwrt.org",
"revision": "r21968-acd8e94d20",
"advanced_mode": "0",
"branch": "SNAPSHOT",
"efi": null,
"profile": "tplink,archer-c6-v3",
"target": "ramips/mt7621",
"version": "SNAPSHOT",
"packages": [
"base-files",
"busybox",
"ca-bundle",
"dnsmasq",
"dropbear",
"firewall4",
"fstools",
"fwtool",
"getrandom",
"hostapd-common",
"iwinfo",
"jansson",
"jshn",
"jsonfilter",
"kernel",
"kmod-crypto-acompress",
"kmod-crypto-crc32c",
"kmod-crypto-hash",
"kmod-gpio-button-hotplug",
"kmod-leds-gpio",
"kmod-lib-crc-ccitt",
"kmod-lib-crc32c",
"kmod-lib-lzo",
"kmod-mt7603",
"kmod-mt7615e",
"kmod-mt7663-firmware-ap",
"kmod-nf-conntrack",
"kmod-nf-conntrack6",
"kmod-nf-flow",
"kmod-nf-log",
"kmod-nf-log6",
"kmod-nf-nat",
"kmod-nf-reject",
"kmod-nf-reject6",
"kmod-nfnetlink",
"kmod-nft-core",
"kmod-nft-fib",
"kmod-nft-nat",
"kmod-nft-offload",
"kmod-ppp",
"kmod-pppoe",
"kmod-pppox",
"kmod-slhc",
"libblobmsg-json",
"libc",
"libiwinfo",
"libiwinfo-data",
"libjson-c",
"libjson-script",
"libmnl",
"libnftnl",
"libnl-tiny",
"libubox",
"libubus",
"libuci",
"libuclient",
"libucode",
"libustream-wolfssl",
"libwolfssl",
"logd",
"luci",
"luci-app-diag-core",
"luci-app-mwan3",
"luci-app-uhttpd",
"luci-nginx",
"luci-ssl",
"luci-ssl-nginx",
"mtd",
"mwan3",
"netifd",
"nftables-json",
"odhcp6c",
"odhcpd-ipv6only",
"openssl-util",
"openwrt-keyring",
"opkg",
"ppp",
"ppp-mod-pppoe",
"procd",
"procd-seccomp",
"procd-ujail",
"ubi-utils",
"ubox",
"ubus",
"ubusd",
"uci",
"uclient-fetch",
"ucode",
"ucode-mod-fs",
"ucode-mod-ubus",
"ucode-mod-uci",
"urandom-seed",
"urngd",
"usign",
"wpad-basic-wolfssl"
],
"diff_packages": true,
"filesystem": "squashfs",
"client": "luci/undefined"
}
STDERR:
Package list missing or not up-to-date, generating it.

Building package index...
Downloading https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_core
Downloading https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_base
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/kmods/5.15.98-1-23ec1f8c05900908d653efdf6254f6ad/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_kmods
Downloading https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/kmods/5.15.98-1-23ec1f8c05900908d653efdf6254f6ad/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_luci
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/packages/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_packages
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/packages/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/routing/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_routing
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/routing/Packages.sig
Signature check passed.
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/telephony/Packages.gz
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/openwrt_telephony
Downloading https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/telephony/Packages.sig
Signature check passed.
Downloading file:packages/Packages
Updated list of available packages in /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/../../../../../../../../../../../home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/dl/imagebuilder
Downloading file:packages/Packages.sig
Signature check failed.
Remove wrong Signature file.
Collected errors:

• check_data_file_clashes: Package libustream-mbedtls20201210 wants to install file /home/aparcar/asu/worker1/cache/SNAPSHOT/ramips/mt7621/build_dir/target-mipsel_24kc_musl/root-ramips/lib/libustream-ssl.so
  But that file is already provided by package * libustream-wolfssl20201210
• opkg_install_cmd: Cannot install package luci-ssl.
  make[2]: *** [Makefile:185: package_install] Error 255
  make[1]: *** [Makefile:150: _call_manifest] Error 2
  make: *** [Makefile:269: manifest] Error 2

Start with the request data and STDERR for profile tplink,archer-c6-v3, then reproduce the SNAPSHOT image build through the ASU service or imagebuilder. Investigate the package conflict between libustream-mbedtls20201210 and libustream-wolfssl20201210; done means the requested firmware image builds without the impossible package selection error.