appsmithorg/appsmith · error · AppsmithPluginException

PE-JSN-4000

PE-JSN-4000

Error message

Plugin failed to parse JSON "{0}"

What it means

Thrown in RowsUpdateMethod.validateExecutionMethodRequest in the catch (JsonProcessingException e) branch (line 87). objectMapper.readTree(body) succeeded in tokenizing but the resulting tree is not a valid row object payload - more precisely this branch is reached when readTree throws (truly malformed JSON), since the IllegalArgumentException branch (271) catches structural-but-wrong shapes. Code: PLUGIN_JSON_PARSE_ERROR (PE-JSN-4000). Message: "Plugin failed to parse JSON \"{0}\"" with the raw body and PARSING_FAILED_EXPECTED_A_ROW_OBJECT_ERROR_MSG + the Jackson error message.

Source

Thrown at app/server/appsmith-plugins/googleSheetsPlugin/src/main/java/com/external/config/RowsUpdateMethod.java:87

                        ErrorMessages.INVALID_TABLE_HEADER_INDEX,
                        e.getMessage());
            }
        } else {
            throw new AppsmithPluginException(
                    AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR, ErrorMessages.INVALID_TABLE_HEADER_INDEX);
        }
        final String body = methodConfig.getRowObjects();
        try {
            this.getRowObjectFromBody(this.objectMapper.readTree(body));
        } catch (IllegalArgumentException e) {
            if (!StringUtils.hasLength(body)) {
                throw new AppsmithPluginException(
                        AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR,
                        ErrorMessages.EMPTY_UPDATE_ROW_OBJECT_MESSAGE);
            }
            throw new AppsmithPluginException(AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR, e.getMessage());
        } catch (JsonProcessingException e) {
            throw new AppsmithPluginException(
                    AppsmithPluginError.PLUGIN_JSON_PARSE_ERROR,
                    methodConfig.getRowObjects(),
                    ErrorMessages.PARSING_FAILED_EXPECTED_A_ROW_OBJECT_ERROR_MSG + " Error: " + e.getMessage());
        }
        return true;
    }

    @Override
    public Mono<Object> executePrerequisites(MethodConfig methodConfig, OAuth2 oauth2) {
        WebClient client =
                WebClientUtils.builder().exchangeStrategies(EXCHANGE_STRATEGIES).build();
        final RowsGetMethod rowsGetMethod = new RowsGetMethod(this.objectMapper);

        final String body = methodConfig.getRowObjects();
        RowObject rowObjectFromBody = null;
        try {
            rowObjectFromBody = this.getRowObjectFromBody(this.objectMapper.readTree(body));
        } catch (JsonProcessingException e) {

View on GitHub (pinned to 8cd9021c24)

Solutions

1. Always JSON.stringify a JS object instead of hand-writing JSON: {{ JSON.stringify({ name: row.name, age: row.age }) }}.
2. Validate client-side: try { JSON.parse(value) } catch and block the run.
3. If pasting JSON, validate with a JSON linter before saving.
4. Avoid template-string interpolation into JSON; build the object then stringify.
5. Check the raw body in the error message - Jackson's error pinpoints the bad token.

Example fix

// Before (hand-written, fragile)
{ "name": "{{Input1.text}}", "age": {{Input2.text}} }
// Input2 empty -> { ..., "age":  } is invalid JSON

// After (safe)
{{ JSON.stringify({ name: Input1.text, age: Number(Input2.text) }) }}

function buildRowJson(obj) {
  // build from a real JS object, never hand-written JSON
  const clean = Object.fromEntries(
    Object.entries(obj).filter(([_, v]) => v !== undefined && v !== null && !Number.isNaN(v))
  );
  const str = JSON.stringify(clean); // throws if cyclic - caller should try/catch
  try { JSON.parse(str); return str; } catch { return null; }
}

function isParsableJson(s) {
  if (typeof s !== 'string' || s.trim() === '') return false;
  try { JSON.parse(s); return true; } catch { return false; }
}

try {
  const body = JSON.stringify(rowObj);
  JSON.parse(body); // sanity
  UpdateRow.run({ rowObjects: body });
} catch (e) {
  showAlert('Row body is not valid JSON: ' + e.message, 'error');
}

When it happens

Trigger: Body is malformed JSON - unbalanced braces, trailing comma, single quotes, unquoted keys, a JS object literal pasted instead of JSON (e.g. {a: 1} instead of {"a": 1}), or a template that produced 'undefined'/'NaN' inside the JSON.

Common situations: Hand-typed JSON in the editor; a JS object literal (not JSON) pasted into the binding; template substitution inserting undefined/NaN which JSON.stringify would have filtered; copy-paste from a console.log of an object.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• PE-JSN-4000
• PE-ARG-5000
• PE-ARG-5000
• PE-ARG-5000
• PE-JSN-4000

AI-assisted analysis of appsmithorg/appsmith@8cd9021c24 (2026-08-12). Data as JSON: /api/errors/c2fbffa874421567. Report an issue: GitHub.