Describe the problem/error/question
I originally experienced this as an intermittent issue, and then yesterday it started to happen consistently. The workflow errors when using the slack node with sendAndWait: message.
What is the error message (if any)?
invalid_blocks
Please share your workflow
(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)
{
“nodes”: [
{
“parameters”: {
“authentication”: “oAuth2”,
“operation”: “sendAndWait”,
“user”: {
“__rl”: true,
“value”: “U04347H5D”,
“mode”: “list”,
“cachedResultName”: “staats”
},
“message”: “=Opportunity Name: {{ $json["Opportunity Name"] }}\n—\nDescription: {{ $json.Description }}\n—\nScore: {{ $json["Final Score"] }}\n—\nRecommendation: {{ $json.Recommendation }}\n–\nDeliverables\n\n{{ $json["Technical Requirements"].map(req => • *${req.Requirement}*: ${req.Description}).join(‘\n’) }}\n—\nSubmission Instructions\n\n{{ $json["Submission Instructons"].map(req => • *${req.Requirement}*: ${req.Description}).join(‘\n’) }}\n—\nQ&A\n\n{{ $json["Q & A"].map(req => • *${req.Question}*: ${req.Answer}).join(‘\n’) }}”,
“approvalOptions”: {
“values”: {
“approvalType”: “double”
}
}
},
“type”: “n8n-nodes-base.slack”,
“typeVersion”: 2.3,
“position”: [
600,
-140
],
“id”: “e243dc09-4afc-42e1-8dc0-11ef8d2c85ac”,
“name”: “Get Approval”,
“webhookId”: “0b6e3fb3-812d-47ba-8c37-331c50e806b3”,
“credentials”: {
“slackOAuth2Api”: {
“id”: “2y20stZQ1YernUU2”,
“name”: “Slack OAuth”
}
}
}
],
“connections”: {
“Get Approval”: {
“main”: [
]
}
},
“pinData”: {}
}
Share the output returned by the last node
{
“errorMessage”: “Slack error response: "invalid_blocks"”,
“errorDetails”: {},
“n8nDetails”: {
“nodeName”: “Get Approval”,
“nodeType”: “n8n-nodes-base.slack”,
“nodeVersion”: 2.3,
“resource”: “message”,
“operation”: “sendAndWait”,
“time”: “2/12/2025, 11:01:13 AM”,
“n8nVersion”: “1.73.1 (Cloud)”,
“binaryDataMode”: “filesystem”,
“stackTrace”: [
“NodeOperationError: Slack error response: "invalid_blocks"”,
" at ExecuteContext.slackApiRequest (/usr/local/lib/node_modules/n8n/node_modules/n8n-nodes-base/dist/nodes/Slack/V2/GenericFunctions.js:61:15)“,
" at processTicksAndRejections (node:internal/process/task_queues:95:5)”,
" at ExecuteContext.execute (/usr/local/lib/node_modules/n8n/node_modules/n8n-nodes-base/dist/nodes/Slack/V2/SlackV2.node.js:297:13)“,
" at WorkflowExecute.runNode (/usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/WorkflowExecute.js:634:19)”,
" at /usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/WorkflowExecute.js:874:51",
" at /usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/WorkflowExecute.js:1305:20"
]
}
}
Information on your n8n setup
- n8n version:
- Database (default: SQLite):
- n8n EXECUTIONS_PROCESS setting (default: own, main):
- Running n8n via (Docker, npm, n8n cloud, desktop app):
- Operating system: