appsmithorg/appsmith · error · AppsmithPluginException

PE-JSN-4000

PE-JSN-4000

Error message

Plugin failed to parse JSON "{0}"

What it means

Thrown by RowsAppendMethod.validateExecutionMethodRequest when objectMapper.readTree throws JsonProcessingException — i.e. the rowObjects string is non-empty, looks like JSON, but is syntactically malformed. Code PE-JSN-4000 maps to PLUGIN_JSON_PARSE_ERROR (message template 'Plugin failed to parse JSON "{0}"', Appsmith category 'Invalid JSON found', INTERNAL_ERROR). The thrown message appends the raw rowObjects and the Jackson parse error.

Source

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

            } catch (NumberFormatException e) {
                throw new AppsmithPluginException(
                        AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR, ErrorMessages.INVALID_TABLE_HEADER_INDEX);
            }
        } else {
            throw new AppsmithPluginException(
                    AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR, ErrorMessages.INVALID_TABLE_HEADER_INDEX);
        }
        JsonNode bodyNode;
        try {
            bodyNode = this.objectMapper.readTree(methodConfig.getRowObjects());
        } catch (IllegalArgumentException e) {
            if (!StringUtils.hasLength(methodConfig.getRowObjects())) {
                throw new AppsmithPluginException(
                        AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR, ErrorMessages.EMPTY_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());
        }

        if (bodyNode.isArray()) {
            throw new AppsmithPluginException(
                    AppsmithPluginError.PLUGIN_EXECUTE_ARGUMENT_ERROR,
                    ErrorMessages.EXPECTED_ROW_OBJECT_BUT_FOUND_ARRAY_ERROR_MSG);
        }
        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);

View on GitHub (pinned to 8cd9021c24)

Solutions

1. Validate the JSON in a linter (jsonlint.com) and fix the syntax error named in the appended 'Error:' detail.
2. Use JSON.stringify in a JS binding so Appsmith serializes correctly: {{ JSON.stringify({Name: 'Alice', Age: 30}) }}.
3. Quote all keys with double quotes and remove trailing commas.

Example fix

// before
{Name: 'Alice', Age: 30,}   // unquoted keys, trailing comma, single quotes

// after
{"Name":"Alice","Age":30}

// Reject malformed JSON before the plugin sees it
String rowObjects = methodConfig.getRowObjects();
try {
    objectMapper.readTree(rowObjects);
} catch (com.fasterxml.jackson.core.JsonProcessingException e) {
    // show e.getMessage() to the user and abort the query
}

boolean isValidJsonObject(ObjectMapper om, String s) {
    try {
        var n = om.readTree(s);
        return n != null && n.isObject();
    } catch (Exception e) { return false; }
}

When it happens

Trigger: Providing a rowObjects string with JSON syntax errors: unquoted keys, trailing commas, single quotes, missing braces, or stray characters. readTree raises JsonProcessingException and the catch wraps it as PLUGIN_JSON_PARSE_ERROR.

Common situations: Hand-typed JSON in the query editor, templated strings that produced malformed output, or copy-paste introducing smart quotes.

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-ARG-5000

AI-assisted analysis of appsmithorg/appsmith@8cd9021c24 (2026-08-12). Data as JSON: /api/errors/1f3d4d774d40cf21. Report an issue: GitHub.