Show message in the frontend if prompt execution raises an exception

execution.py

@@ -258,27 +258,31 @@ class PromptExecutor:
         self.old_prompt = {}
         self.server = server
 
-    def handle_execution_error(self, prompt_id, current_outputs, executed, error, ex):
+    def handle_execution_error(self, prompt_id, prompt, current_outputs, executed, error, ex):
+        node_id = error["node_id"]
+        class_type = prompt[node_id]["class_type"]
+
         # First, send back the status to the frontend depending
         # on the exception type
         if isinstance(ex, comfy.model_management.InterruptProcessingException):
             mes = {
                 "prompt_id": prompt_id,
+                "node_id": node_id,
+                "node_type": class_type,
                 "executed": list(executed),
-
-                "node_id": error["node_id"],
             }
             self.server.send_sync("execution_interrupted", mes, self.server.client_id)
         else:
             if self.server.client_id is not None:
                 mes = {
                     "prompt_id": prompt_id,
+                    "node_id": node_id,
+                    "node_type": class_type,
                     "executed": list(executed),
 
                     "message": error["message"],
                     "exception_type": error["exception_type"],
                     "traceback": error["traceback"],
-                    "node_id": error["node_id"],
                     "current_inputs": error["current_inputs"],
                     "current_outputs": error["current_outputs"],
                 }
@@ -346,7 +350,7 @@ class PromptExecutor:
                 # error was raised
                 success, error, ex = recursive_execute(self.server, prompt, self.outputs, output_node_id, extra_data, executed, prompt_id, self.outputs_ui)
                 if success is not True:
-                    self.handle_execution_error(prompt_id, current_outputs, executed, error, ex)
+                    self.handle_execution_error(prompt_id, prompt, current_outputs, executed, error, ex)
 
             for x in executed:
                 self.old_prompt[x] = copy.deepcopy(prompt[x])

web/scripts/api.js

@@ -88,6 +88,12 @@ class ComfyApi extends EventTarget {
 					case "executed":
 						this.dispatchEvent(new CustomEvent("executed", { detail: msg.data }));
 						break;
+					case "execution_start":
+						this.dispatchEvent(new CustomEvent("execution_start", { detail: msg.data }));
+						break;
+					case "execution_error":
+						this.dispatchEvent(new CustomEvent("execution_error", { detail: msg.data }));
+						break;
 					default:
 						if (this.#registered.has(msg.type)) {
 							this.dispatchEvent(new CustomEvent(msg.type, { detail: msg.data }));

web/scripts/app.js

@@ -784,8 +784,10 @@ export class ComfyApp {
 				color = "red";
 				lineWidth = 2;
 			}
-
+			else if (self.lastExecutionError && +self.lastExecutionError.node_id === node.id) {
-			self.graphTime = Date.now()
+				color = "#f0f";
+				lineWidth = 2;
+			}
 
 			if (color) {
 				const shape = node._shape || node.constructor.shape || LiteGraph.ROUND_SHAPE;
@@ -895,6 +897,17 @@ export class ComfyApp {
 			}
 		});
 
+		api.addEventListener("execution_start", ({ detail }) => {
+			this.lastExecutionError = null
+		});
+
+		api.addEventListener("execution_error", ({ detail }) => {
+			this.lastExecutionError = detail;
+			const formattedError = this.#formatExecutionError(detail);
+			this.ui.dialog.show(formattedError);
+			this.canvas.draw(true, true);
+		});
+
 		api.init();
 	}
 
@@ -1269,7 +1282,7 @@ export class ComfyApp {
 		return { workflow, output };
 	}
 
-	#formatError(error) {
+	#formatPromptError(error) {
 		if (error == null) {
 			return "(unknown error)"
 		}
@@ -1294,6 +1307,18 @@ export class ComfyApp {
 		return "(unknown error)"
 	}
 
+	#formatExecutionError(error) {
+		if (error == null) {
+			return "(unknown error)"
+		}
+
+		const traceback = error.traceback.join("")
+		const nodeId = error.node_id
+		const nodeType = error.node_type
+
+		return `Error occurred when executing ${nodeType}:\n\n${error.message}\n\n${traceback}`
+	}
+
 	async queuePrompt(number, batchCount = 1) {
 		this.#queueItems.push({ number, batchCount });
 
@@ -1315,7 +1340,7 @@ export class ComfyApp {
 					try {
 						await api.queuePrompt(number, p);
 					} catch (error) {
-						const formattedError = this.#formatError(error)
+						const formattedError = this.#formatPromptError(error)
 						this.ui.dialog.show(formattedError);
 						if (error.response) {
 							this.lastPromptError = error.response;
@@ -1419,7 +1444,7 @@ export class ComfyApp {
 	clean() {
 		this.nodeOutputs = {};
 		this.lastPromptError = null;
-		this.graphTime = null
+		this.lastExecutionError = null;
 	}
 }