plandex-ai/plandex · error

Error marshalling plan state:

Error message

Error marshalling plan state: 

What it means

CurrentPlanHandler succeeded in building the CurrentPlanState but json.Marshal(planState) failed, so it returns 500 'Error marshalling plan state'. This is nearly impossible for well-formed state and usually indicates a custom MarshalJSON implementation failing on corrupt or unexpected data.

Source

Thrown at app/server/handlers/plans_changes.go:97

		if err != nil {
			return fmt.Errorf("error getting current plan state: %v", err)
		}

		return nil
	})

	if err != nil {
		log.Printf("Error getting current plan state: %v\n", err)
		http.Error(w, "Error getting current plan state: "+err.Error(), http.StatusInternalServerError)
		return
	}

	jsonBytes, err := json.Marshal(planState)

	if err != nil {
		log.Printf("Error marshalling plan state: %v\n", err)
		http.Error(w, "Error marshalling plan state: "+err.Error(), http.StatusInternalServerError)
		return
	}

	log.Println("Successfully retrieved current plan state")

	w.Write(jsonBytes)
}

func ApplyPlanHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("Received request for ApplyPlanHandler")

	auth := Authenticate(w, r, true)
	if auth == nil {
		return
	}

	vars := mux.Vars(r)
	planId := vars["planId"]

View on GitHub (pinned to e2d772072e)

Solutions

1. Check the server log for the marshal error message to identify which field failed
2. Upgrade/downgrade so client and server share the same plandex-shared version
3. Repair the plan by rejecting all pending changes and re-running, or restore from backup
4. If reproducible, file an issue with the marshal error — it indicates a serialization bug

Example fix

null

null

null

const res = await fetch(currentPlanUrl);
if (res.status === 500 && (await res.text()).includes('Error marshalling plan state')) {
  // serialization bug / corrupt state: resync shared versions, repair plan, report issue
}

When it happens

Trigger: CurrentPlanState (or a nested field with custom MarshalJSON, e.g. context/token data) contains values its marshaller cannot serialize; corrupted rows producing inconsistent state after an interrupted apply.

Common situations: Plan data written by a different (older/newer) server version with incompatible schema; NaN/invalid numeric values in custom serializers; corrupted plan repo after a crash mid-write.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• error marshalling auth header: %v
• error marshalling models: %v
• error marshalling account credentials: %v
• error marshalling model pack: %v
• error marshalling current plan: %v

AI-assisted analysis of plandex-ai/plandex@e2d772072e (2026-09-05). Data as JSON: /api/errors/9801fe540f0db9c4. Report an issue: GitHub.