{"record":{"id":"72319bedf794fc39","repo":"hashicorp/packer","slug":"unsupported-remote-protocol-major-version-d-the","errorCode":null,"errorMessage":"unsupported remote protocol MAJOR version %d. The current MAJOR protocol version is %d. This version of Packer can only communicate with plugins using that version","messagePattern":"unsupported remote protocol MAJOR version (.+?)\\. The current MAJOR protocol version is (.+?)\\. This version of Packer can only communicate with plugins using that version","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"packer/plugin-getter/plugins.go","lineNumber":535,"sourceCode":"\n\tlocalVersion := localAPIVersion\n\tif binOpts.APIVersionMajor != pluginsdk.APIVersionMajor ||\n\t\tbinOpts.APIVersionMinor != pluginsdk.APIVersionMinor {\n\t\tvar err error\n\n\t\tlocalVersion, err = NewAPIVersion(fmt.Sprintf(\"x%s.%s\", binOpts.APIVersionMajor, binOpts.APIVersionMinor))\n\t\tif err != nil {\n\t\t\treturn fmt.Errorf(\"Failed to parse API Version from constraints: %s\", err)\n\t\t}\n\t}\n\n\tremoteVersion, err := NewAPIVersion(remoteProt)\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tif localVersion.Major != remoteVersion.Major {\n\t\treturn fmt.Errorf(\"unsupported remote protocol MAJOR version %d. The current MAJOR protocol version is %d.\"+\n\t\t\t\" This version of Packer can only communicate with plugins using that version\", remoteVersion.Major, localVersion.Major)\n\t}\n\n\tif remoteVersion.Minor > localVersion.Minor {\n\t\treturn fmt.Errorf(\"unsupported remote protocol MINOR version %d. The supported MINOR protocol versions are version %d and below. \"+\n\t\t\t\"Please upgrade Packer or use an older version of the plugin if possible\", remoteVersion.Minor, localVersion.Minor)\n\t}\n\n\treturn nil\n}\n\nfunc (gp *GetOptions) Version() string {\n\treturn \"v\" + gp.version.String()\n}\n\nfunc (gp *GetOptions) VersionString() string {\n\treturn gp.version.String()\n}","sourceCodeStart":517,"sourceCodeEnd":553,"githubUrl":"https://github.com/hashicorp/packer/blob/eb36e3c3e48a036f3e8cc94087636ee72e1303c9/packer/plugin-getter/plugins.go#L517-L553","documentation":"CheckProtocolVersion() rejects a plugin whose advertised protocol MAJOR version differs from the one this Packer binary supports. The gRPC plugin protocol MAJOR version defines wire compatibility, so a mismatch means Packer and the plugin cannot communicate at all.","triggerScenarios":"Installing or validating a plugin whose entry.ProtVersion parses to a Major != the local pluginsdk.APIVersionMajor — e.g. an old plugin built against protocol x4.x, or a future plugin built against x6.0, installed by current Packer (x5.x).","commonSituations":"Pinning a very old plugin release for legacy templates; testing a plugin built from a protocol-breaking SDK branch; downloading a plugin whose checksums file includes assets from multiple protocol generations.","solutions":["Upgrade Packer to a version whose protocol MAJOR matches the plugin (or vice versa).","Pick a different plugin version whose protocol MAJOR matches (usually the newest release compatible with your Packer).","Rebuild the plugin against the current packer-plugin-sdk so it reports the current MAJOR protocol version."],"exampleFix":"// before: pins a protocol-4-era release\nmyplug = { version = \"= 0.0.10\", source = \"github.com/foo/myplug\" }\n// after\nmyplug = { version = \">= 1.0.0\", source = \"github.com/foo/myplug\" }","handlingStrategy":"validation","validationCode":"local, _ := NewAPIVersion(fmt.Sprintf(\"x%s.%s\", pluginsdk.APIVersionMajor, pluginsdk.APIVersionMinor))\nremote, err := NewAPIVersion(entry.ProtVersion)\nif err == nil && local.Major != remote.Major {\n\treturn fmt.Errorf(\"plugin protocol x%d.x incompatible with packer x%d.x\", remote.Major, local.Major)\n}","typeGuard":null,"tryCatchPattern":"if err := binOpts.CheckProtocolVersion(entry.ProtVersion); err != nil {\n\tif strings.Contains(err.Error(), \"MAJOR version\") {\n\t\treturn fmt.Errorf(\"try a different plugin release or upgrade packer: %w\", err)\n\t}\n}","preventionTips":["Match plugin releases to your Packer version before pinning","Rebuild old plugins against the current packer-plugin-sdk","Watch Packer release notes for protocol MAJOR bumps"],"tags":["plugin-getter","protocol-version","incompatible-version","plugin-install"],"backgroundTag":"protocol-major-version-mismatch","analyzedSha":"eb36e3c3e48a036f3e8cc94087636ee72e1303c9","analyzedAt":"2026-09-05T13:20:43.127Z","contentChangedAt":"2026-09-05T13:20:43.127Z","schemaVersion":2},"datasetVersion":"2026-09-12T17:17:11.597Z"}