Scenario Building Errors
Below are common errors that occur when configuring nodes, using variable substitutions, and running scenarios. Variable format is described in Variable templates.
Variable syntax errors
The correct variable format and placeholders are described on Passing data. The platform uses its own variable format. Plain names like {{first_name}}, non-Latin characters, or bare operators inside {{ }} are not valid.
Messages: Unexpected symbol: f — invalid variable format {{first_name}}, Unexpected symbol: 乙 — non-Latin character, Unexpected symbol: & — expression {{&&}} contains invalid operator
Cause: plain name {{first_name}} used; non-Latin characters in the name; or operator (&&, ||) used directly inside {{ }}.
What to do
- Node output:
{{$nodeNumber.field}}, e.g.{{$11.first_name}}. - Scenario variable:
{{_.variableName}}, global:{{%.name}}. - Insert substitutions via the variable helper widget or see Variable templates.
Expression parsing errors
The expression engine cannot parse a formula, condition, or function call.
Messages: Expression parsing error: unsupported expression, Expression error: split() called with three arguments, invalid syntax near '&&'
Cause: calling functions like randomString() or split() with unsupported syntax; using && / || directly inside {{ }}; unmatched brackets or quotes.
What to do
- Move complex logic to a JavaScript node.
- For conditions, use a route filter or an IF-style node.
- Validate the expression in the editor before saving.
Empty required fields
A mandatory node parameter has no value at execution time.
Messages: required field "Message ID" is empty, required field "Chat ID" is empty, required field "Search Value" is empty
Cause: field left blank or set to a non-existent variable {{xxx}}; previous node returned no data; variable path does not match the node output.
What to do
- Map the field to previous node output:
{{$nodeNumber.field}}, e.g.{{$11.id}}. - Check the previous node output in execution history.
- Add a condition to verify the value exists before passing it.
Undefined / null values
The node tries to access a property on a value that does not exist.
Messages: Cannot read properties of undefined (reading "0"), Cannot read properties of null (reading 'access_token'), undefined is not an array or an array-like object
Cause: previous node returned empty or unexpected data; variable path points to a non-existent field; auth token missing or expired.
What to do
- Log the previous node output to verify its structure.
- In a JavaScript node use optional chaining:
data?.field ?? ''. - Add a condition to check the value exists before using it.
JSON parse errors
The JSON Parse node receives input that is not valid JSON.
Messages: SyntaxError: invalid or unexpected token, Unexpected token 'R' — input is plain text, Bad control character in string literal, Parameter "..." is invalid JSON
Cause: previous node returned plain text, HTML, or error message; AI node output wrapped in markdown fences ```json; unescaped newlines in JSON; input is CSV, XML, or other non-JSON format.
What to do
- Log the raw output before the JSON Parse node to inspect it.
- Use a JS node to strip markdown fences if needed.
- In AI node prompts, add "respond only in valid JSON, no markdown".
Not iterable / empty output
A node expects an array but receives a single object, null, or nothing.
Messages: rows_input is not iterable, undefined is not an array or an array-like object, get last records empty list
Cause: passing a single object where an array is expected; previous node returned empty results; wrong data structure from upstream node.
What to do
- Wrap single objects in an array in a JS node:
[data]. - Add a condition to handle empty arrays before iterating.
- Ensure the source returns an array before the node that expects it.
Execution timeout
Scenario or node exceeds allowed execution time.
Messages: Scenario execution time exceeded, TimeoutError: Waiting for selector failed: 60000ms exceeded, 524 timeout — webhook scenario marked Canceled
Cause: processing too many records in one run; inefficient loop or missing filters; Headless Browser waiting for a selector that never appears; webhook needs response in <3s but scenario is too slow.
What to do
- Split large batches using an Iterator.
- Add filters to reduce data volume before heavy operations.
- For fast webhook response: return 200 immediately, process asynchronously.
- Use enhanced compute (Engine Tier 1) for heavy scenarios.
HTTP Request node errors
Error in the HTTP Request node: invalid or empty URL, unsupported protocol, or control characters in the URL field.
Messages: unsupported protocol scheme "", URL missing http:// or https://, invalid control character in URL, Invalid URL — empty or malformed URL
Cause: variable for URL resolved to null (URL becomes https://null); URL built by concatenation with missing base; hidden newline or carriage return in the URL field.
What to do
- Log the URL variable value before the HTTP Request node.
- Add a condition so the request runs only if URL is not null or empty.
- Use a JS node to trim and validate the URL:
url.trim().