{"record":{"id":"bde8e368c9f6fb48","repo":"XTLS/Xray-core","slug":"maxconnectionreceivewindow-must-be-at-least-16384","errorCode":null,"errorMessage":"MaxConnectionReceiveWindow must be at least 16384","messagePattern":"MaxConnectionReceiveWindow must be at least 16384","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"infra/conf/transport_internet.go","lineNumber":270,"sourceCode":"\t\t\tdefault:\n\t\t\t\treturn nil, errors.New(\"unknown congestion control: \", c.FinalMask.QuicParams.Congestion, \", valid values: reno, bbr, brutal, force-brutal\")\n\t\t\t}\n\n\t\t\tif (c.FinalMask.QuicParams.UdpHop.Interval.From != 0 && c.FinalMask.QuicParams.UdpHop.Interval.From < 5) || (c.FinalMask.QuicParams.UdpHop.Interval.To != 0 && c.FinalMask.QuicParams.UdpHop.Interval.To < 5) {\n\t\t\t\treturn nil, errors.New(\"Interval must be at least 5\")\n\t\t\t}\n\n\t\t\tif c.FinalMask.QuicParams.InitStreamReceiveWindow > 0 && c.FinalMask.QuicParams.InitStreamReceiveWindow < 16384 {\n\t\t\t\treturn nil, errors.New(\"InitStreamReceiveWindow must be at least 16384\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.MaxStreamReceiveWindow > 0 && c.FinalMask.QuicParams.MaxStreamReceiveWindow < 16384 {\n\t\t\t\treturn nil, errors.New(\"MaxStreamReceiveWindow must be at least 16384\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.InitConnectionReceiveWindow > 0 && c.FinalMask.QuicParams.InitConnectionReceiveWindow < 16384 {\n\t\t\t\treturn nil, errors.New(\"InitConnectionReceiveWindow must be at least 16384\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.MaxConnectionReceiveWindow > 0 && c.FinalMask.QuicParams.MaxConnectionReceiveWindow < 16384 {\n\t\t\t\treturn nil, errors.New(\"MaxConnectionReceiveWindow must be at least 16384\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.MaxIdleTimeout != 0 && (c.FinalMask.QuicParams.MaxIdleTimeout < 4 || c.FinalMask.QuicParams.MaxIdleTimeout > 120) {\n\t\t\t\treturn nil, errors.New(\"MaxIdleTimeout must be between 4 and 120\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.KeepAlivePeriod != 0 && (c.FinalMask.QuicParams.KeepAlivePeriod < 2 || c.FinalMask.QuicParams.KeepAlivePeriod > 60) {\n\t\t\t\treturn nil, errors.New(\"KeepAlivePeriod must be between 2 and 60\")\n\t\t\t}\n\t\t\tif c.FinalMask.QuicParams.MaxIncomingStreams != 0 && c.FinalMask.QuicParams.MaxIncomingStreams < 8 {\n\t\t\t\treturn nil, errors.New(\"MaxIncomingStreams must be at least 8\")\n\t\t\t}\n\n\t\t\tif c.FinalMask.QuicParams.Debug {\n\t\t\t\tos.Setenv(\"HYSTERIA_BBR_DEBUG\", \"true\")\n\t\t\t\tos.Setenv(\"HYSTERIA_BRUTAL_DEBUG\", \"true\")\n\t\t\t}\n\n\t\t\tconfig.QuicParams = &internet.QuicParams{\n\t\t\t\tCongestion: c.FinalMask.QuicParams.Congestion,","sourceCodeStart":252,"sourceCodeEnd":288,"githubUrl":"https://github.com/XTLS/Xray-core/blob/7d214f8b094f75322fa3990f8aadad1c912f24f5/infra/conf/transport_internet.go#L252-L288","documentation":"The 16384-byte minimum for the connection-level maximum receive window (finalMask.quicParams.maxConnectionReceiveWindow). Positive values below 16 KiB fail validation; 0 is the default. This is the last of the four window floor checks.","triggerScenarios":"\"quicParams\": { \"maxConnectionReceiveWindow\": 8192 }.","commonSituations":"Memory-tuning that crosses the protocol floor; inconsistent window sets where max < init; stale values from older configs.","solutions":["Set maxConnectionReceiveWindow >= 16384 bytes (e.g. 8388608).","Or omit it for the default.","Verify max >= init for both stream and connection windows."],"exampleFix":"// before\n\"quicParams\": { \"maxConnectionReceiveWindow\": 8192 }\n// after\n\"quicParams\": { \"maxConnectionReceiveWindow\": 8388608 }","handlingStrategy":"validation","validationCode":"func connectionWindowsOK(qp map[string]any) bool {\n    return windowFloorOK(qp[\"maxConnectionReceiveWindow\"], 16384) &&\n        windowFloorOK(qp[\"initConnectionReceiveWindow\"], 16384)\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Tune the four window knobs as a set; do not shrink max below init.","Use byte literals (e.g. 8388608) in configs to avoid unit ambiguity.","Re-run config validation after any QUIC tuning change."],"tags":["go","xray","config","quic","flow-control","validation"],"backgroundTag":null,"analyzedSha":"7d214f8b094f75322fa3990f8aadad1c912f24f5","analyzedAt":"2026-08-15T14:26:24.325Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}