- Still not fixed in 4.26.
- Flag UE_USE_SYSTEM_MONO still undocumented.
- Mono 6.12 would fail anyway because versions >5 are not properly treated. I fixed it in Engine/Build/BatchFiles/Linux/SetupMono.sh by extending the following line: if [ ${MONO_VERSION[0]} -ge 6 ] || [ ${MONO_VERSION[1]} -ge 0 ] || [ ${MONO_VERSION[2]} -ge 2 ]; then