{"record":{"id":"a219294d9ba5597b","repo":"hashicorp/nomad","slug":"failed-to-decode-taskconfig-state-from-handle-v-a21929","errorCode":null,"errorMessage":"failed to decode taskConfig state from handle: %v","messagePattern":"failed to decode taskConfig state from handle: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"drivers/qemu/driver.go","lineNumber":303,"sourceCode":"\nfunc (d *Driver) RecoverTask(handle *drivers.TaskHandle) error {\n\tif handle == nil {\n\t\treturn fmt.Errorf(\"error: handle cannot be nil\")\n\t}\n\n\t// If already attached to handle there's nothing to recover.\n\tif _, ok := d.tasks.Get(handle.Config.ID); ok {\n\t\td.logger.Trace(\"nothing to recover; task already exists\",\n\t\t\t\"task_id\", handle.Config.ID,\n\t\t\t\"task_name\", handle.Config.Name,\n\t\t)\n\t\treturn nil\n\t}\n\n\tvar taskState TaskState\n\tif err := handle.GetDriverState(&taskState); err != nil {\n\t\td.logger.Error(\"failed to decode taskConfig state from handle\", \"error\", err, \"task_id\", handle.Config.ID)\n\t\treturn fmt.Errorf(\"failed to decode taskConfig state from handle: %v\", err)\n\t}\n\n\tplugRC, err := pstructs.ReattachConfigToGoPlugin(taskState.ReattachConfig)\n\tif err != nil {\n\t\td.logger.Error(\"failed to build ReattachConfig from taskConfig state\", \"error\", err, \"task_id\", handle.Config.ID)\n\t\treturn fmt.Errorf(\"failed to build ReattachConfig from taskConfig state: %v\", err)\n\t}\n\n\texecImpl, pluginClient, err := executor.ReattachToExecutor(\n\t\tplugRC,\n\t\td.logger.With(\"task_name\", handle.Config.Name, \"alloc_id\", handle.Config.AllocID),\n\t\td.nomadConfig.Topology.Compute(),\n\t)\n\tif err != nil {\n\t\td.logger.Error(\"failed to reattach to executor\", \"error\", err, \"task_id\", handle.Config.ID)\n\t\treturn fmt.Errorf(\"failed to reattach to executor: %v\", err)\n\t}\n","sourceCodeStart":285,"sourceCodeEnd":321,"githubUrl":"https://github.com/hashicorp/nomad/blob/482b49bf1aec006f089bcfc7e632d8f6ac303e5e/drivers/qemu/driver.go#L285-L321","documentation":"RecoverTask reads the persisted TaskState (containing the executor's reattach config) from the handle via GetDriverState. If the stored blob cannot be decoded into TaskState, recovery cannot proceed and this wrapped error is returned.","triggerScenarios":"Calling RecoverTask with a handle whose driver state was written by a different Nomad/driver version, whose state bytes are corrupt, or whose driver state was never set.","commonSituations":"Nomad client upgraded between agent restarts so the persisted state schema no longer matches; partially written state files after a crash; recovery attempted on a handle created by another driver.","solutions":["If the underlying task is gone or state is unrecoverable, let the allocation fail and reschedule rather than recovering.","Verify the Nomad client and server are on compatible versions; state format can change across upgrades.","Check the logged inner error for gob/JSON decode details to identify the schema mismatch."],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"err := d.RecoverTask(handle)\nif err != nil && strings.Contains(err.Error(), \"failed to decode taskConfig state\") {\n    // state is unreadable; fall back to rescheduling instead of retrying recovery\n    return reschedule(allocID)\n}","preventionTips":["Keep Nomad client and server versions consistent across restarts.","Avoid restoring state files from incompatible Nomad versions onto a client."],"tags":["nomad","qemu-driver","state-deserialization","recover-task"],"backgroundTag":"driver-state-decode-failed","analyzedSha":"482b49bf1aec006f089bcfc7e632d8f6ac303e5e","analyzedAt":"2026-09-04T07:54:14.808Z","contentChangedAt":"2026-09-04T07:54:14.808Z","schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}