No credential was presented, or the one presented did not resolve. Forge fails loudly here rather than silently downgrading to anonymous access.
Forge deliberately does not silently degrade. If a credential is presented and does not resolve, the request fails with 401 rather than being treated as anonymous — a silent downgrade would let a revoked key look like it was still working while quietly losing identity, history, and triggers.
One MCP endpoint serves every protocol adapter. 16,908 curated mappings, 366 canonical fields.
Other HTTP / REST codes: 402 403 422 429
Equipment that speaks HTTP / REST: Caterpillar Cummins Haas MiR (Mobile Industrial Robots) Universal Robots OTTO Motors 6 River Systems AGILOX Detroit Diesel Fetch Robotics
Other protocols: Modbus OPC UA MQTT / Sparkplug B FANUC FOCAS EtherNet/IP PROFINET / S7 BACnet/IP J1939 (CAN) MTConnect ROS 2 (DDS) SNMP MAVLink CSV ingest