{"record":{"id":"925b2a56d4550459","repo":"XTLS/Xray-core","slug":"initconnectionreceivewindow-must-be-at-least-16384","errorCode":null,"errorMessage":"InitConnectionReceiveWindow must be at least 16384","messagePattern":"InitConnectionReceiveWindow must be at least 16384","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"infra/conf/transport_internet.go","lineNumber":267,"sourceCode":"\t\t\t\tif up == 0 {\n\t\t\t\t\treturn nil, errors.New(\"force-brutal requires up\")\n\t\t\t\t}\n\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}","sourceCodeStart":249,"sourceCodeEnd":285,"githubUrl":"https://github.com/XTLS/Xray-core/blob/7d214f8b094f75322fa3990f8aadad1c912f24f5/infra/conf/transport_internet.go#L249-L285","documentation":"The 16384-byte minimum applied to the connection-level initial receive window (finalMask.quicParams.initConnectionReceiveWindow). Positive values below 16 KiB are rejected; 0 keeps the default. Connection windows must be at least as large as stream windows for QUIC flow control to function.","triggerScenarios":"\"quicParams\": { \"initConnectionReceiveWindow\": 1024 }.","commonSituations":"Shrinking all window knobs uniformly below the floor; forgetting this field when copying a tuned set of QUIC parameters; unit mistakes.","solutions":["Set initConnectionReceiveWindow >= 16384 bytes (commonly a few MiB, e.g. 8388608).","Or remove the field to accept the default.","Keep it >= initStreamReceiveWindow."],"exampleFix":"// before\n\"quicParams\": { \"initConnectionReceiveWindow\": 1024 }\n// after\n\"quicParams\": { \"initConnectionReceiveWindow\": 8388608 }","handlingStrategy":"validation","validationCode":"func connectionInitWindowOK(qp map[string]any) bool {\n    return windowFloorOK(qp[\"initConnectionReceiveWindow\"], 16384)\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Set connection windows >= stream windows, never below 16384 bytes.","Prefer omitting window fields unless profiling shows a need.","Keep a canonical quicParams snippet that already passes all floors."],"tags":["go","xray","config","quic","flow-control","validation"],"backgroundTag":null,"analyzedSha":"7d214f8b094f75322fa3990f8aadad1c912f24f5","analyzedAt":"2026-08-15T14:26:24.325Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}