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Error message reference

What a message means and what to do about it. Grouped by where you see it. Copy the exact text into the page's search to find it quickly.

Expressions

[EXPR-ERROR: Node "X" not found. Available: [A, B, C]]

Meaning: an expression names a node that does not exist, or did not run in this execution.

Fix: use the exact display name. Names are case-sensitive. Insert the reference with the data picker to avoid typos. See Debugging expressions.

[EXPR-ERROR: unknown reference "x.output.y" — expected $node["Name"], $trigger, $workflow, $input, or $env. …]

Meaning: you used a shorthand without a Flero root.

Fix: wrap the node name: {{ $node["x"].output.y }}.

[EXPR-ERROR: <other reason>]

Meaning: the path could not be followed, for example an index past the end of a list, or a property of a value that is null.

Fix: open the upstream node's output and check the real shape of the data.

Workspace variable "NAME" is not set.

Meaning: the node reads {{ $env.NAME }} and the workspace has no such variable. The node fails before it runs.

Fix: an owner or admin adds the variable under Settings → Workspace → Variables.

Running workflows

Node execution timed out after <N>ms

Meaning: the node ran past the timeout set in its Node Settings.

Fix: raise the timeout, or find out why the call is slow. Nodes have no timeout unless you set one.

The worker running this execution stopped responding … use Rerun to run it again.

Meaning: the server running the workflow restarted or crashed mid-run, and did not come back within 3 minutes. The run was marked failed. Nothing was re-run automatically.

Fix: check what the run already did, then use Rerun.

Workspace monthly AI Agent node budget exceeded: $X / $Y. Increase the AI Agent node budget in workspace settings to continue.

Meaning: the workspace has spent its monthly limit for AI nodes. The AI Builder has its own limit with a matching message.

Fix: the workspace owner raises the limit under Settings → Workspace → AI Budgets, or you wait for the next month. See AI budgets.

Credential not found: <id>. …

Meaning: an AI node points to a credential that was deleted or that you cannot use.

Fix: pick another credential in the node's inspector.

HTTP Request and connector nodes

Status Meaning Fix
401 Unauthorized The service rejected the credential: expired, revoked or wrong Reconnect or replace the credential. A credential marked "Reconnect required" needs to be signed in again.
403 Forbidden The credential is valid but lacks permission Check the scopes the service needs. See the connector's page.
404 Not Found Wrong URL, or the record does not exist Check the URL and the ids you pass
429 Too Many Requests You hit the service's rate limit The HTTP Request node retries 429 responses 3 times by default and honours Retry-After. Add a Delay between calls or slow the trigger.
5xx The service had a problem Set the node's error mode to retry in Node Settings

Connector nodes return { success, statusCode, data, operation }. Read statusCode and data in the node's output for the service's own error message.

Webhook triggers

Response Meaning Fix
404 Webhook not found The workflow is not active, the trigger is disabled, or the path is wrong Activate the workflow and check the path
405 Method not allowed The request used a different HTTP method from the trigger's Match the method
401 Missing webhook signature The trigger has a Secret Key and the request is unsigned Sign the request. See Webhook trigger → Security.
401 Invalid webhook signature The signature does not match Check the secret on both sides
400 Invalid JSON payload The body is not valid JSON Send JSON with Content-Type: application/json

Signing in

Message Meaning
Invalid credentials Wrong email or password
Too many attempts Too many failed attempts on this account. Wait before trying again.
Please accept your invite before logging in. The account was invited but not set up. Use the invite link.
Your access has been removed. Contact your administrator. You were removed from your last workspace. An admin can add you back.
Invalid code. N attempts remaining. Wrong authenticator code. Check your phone's clock.

Invitations and members

Message Meaning
Invitation not valid / Invite token has expired The 24-hour link has expired or was already used. Ask for a new invitation.
User is already a member of this workspace Nothing to do. They already have access.
Invitation email failed The person was added, but the email did not send. Copy the link and send it yourself.
Forbidden: Only workspace owner or admin can invite members Only owners and admins can invite
Forbidden: Only workspace owner can update settings Only the owner can save workspace name, quotas and AI budgets
You don't have access to organization settings You are not an organization member

Import

Unrecognized workflow format

Meaning: the file is neither a Flero nor an n8n workflow export.

Fix: export the workflow again from its source. See Import and export.

Flero API

See API errors and limits.

Something not listed?

Contact support with the exact text of the error, copied rather than paraphrased, and the execution ID.

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