apache/dolphinscheduler · warning · ServiceException

The file type: ${fileExtension} cannot be fetched

Error message

The file type: ${fileExtension} cannot be fetched

What it means

exceptionFileContentCannotFetch checks the extension of the requested file against FILE_SUFFIXES_WHICH_CAN_FETCH_CONTENT (a whitelist of text-like suffixes such as .sql, .sh, .py, .txt). If the extension is not in the whitelist, viewing the file's content via the API is refused with ServiceException("The file type: {ext} cannot be fetched"), because binary files cannot be rendered as text.

Source

Thrown at dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/validator/resource/AbstractResourceValidator.java:83

        }
    }

    public void exceptionFileInvalidated(MultipartFile file) {
        if (file == null) {
            throw new ServiceException("The file is null");
        }
    }

    public void exceptionFileContentInvalidated(String fileContent) {
        if (StringUtils.isEmpty(fileContent)) {
            throw new ServiceException("The file content is null");
        }
    }

    public void exceptionFileContentCannotFetch(String fileAbsolutePath) {
        String fileExtension = Files.getFileExtension(fileAbsolutePath);
        if (!FILE_SUFFIXES_WHICH_CAN_FETCH_CONTENT.contains(fileExtension)) {
            throw new ServiceException("The file type: " + fileExtension + " cannot be fetched");
        }
    }

    public void exceptionResourceNotExists(String resourceAbsolutePath) {
        if (!storageOperator.exists(resourceAbsolutePath)) {
            throw new ServiceException("Thr resource is not exists: " + resourceAbsolutePath);
        }
    }

    public void exceptionResourceExists(String resourceAbsolutePath) {
        if (storageOperator.exists(resourceAbsolutePath)) {
            throw new ServiceException("The resource is already exist: " + resourceAbsolutePath);
        }
    }

    public void exceptionResourceIsNotDirectory(String resourceAbsolutePath) {
        if (StringUtils.isNotEmpty(Files.getFileExtension(resourceAbsolutePath))) {
            throw new ServiceException("The path is not a directory: " + resourceAbsolutePath);

View on GitHub (pinned to 02eac45a1b)

Solutions

1. Download the file instead of fetching inline content for binary types (jar, zip, images, etc.).
2. Rename/convert the file to a whitelisted text extension if it truly is text (and re-upload if needed).
3. If a new text type is legitimately needed, add its extension to FILE_SUFFIXES_WHICH_CAN_FETCH_CONTENT in the source and redeploy.

Example fix

// before
GET /resources/view?path=/alice/resources/app.jar   // binary
// after
GET /resources/download?path=/alice/resources/app.jar  // or view a .sql/.sh/.py file instead

// client-side pre-check against the server whitelist
const viewable = ['.sh', '.bat', '.sql', '.py', '.txt', '.md', '.properties', '.yml', '.yaml', '.json', '.xml'];
if (!viewable.includes(extension.toLowerCase())) {
    // use the download endpoint instead of view-content
}

function isViewableTextFile(fileName) {
  const ext = fileName.slice(fileName.lastIndexOf('.') + 1).toLowerCase();
  return ['.sql', '.sh', '.py', '.txt', '.md', '.yml', '.yaml', '.json', '.xml', '.properties'].includes('.' + ext);
}

try {
    // view resource content
} catch (ServiceException e) {
    if (e.getMessage().startsWith("The file type:")) {
        // fall back to the download endpoint for this file
    } else throw e;
}

When it happens

Trigger: Calling the 'view resource content' endpoint for a binary file (e.g. .jar, .zip, .xlsx, .tar.gz) or a file with an unusual/missing extension.

Common situations: User clicks 'view' in the resource center on an uploaded jar/zip; extension uppercase or non-standard (e.g. .SQL vs .sql) not matching the whitelist; uploading files whose extension was changed after creation.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Can not find valid resource by name %s
• Unsupported executeType: {0}
• 20016
• ILLEGAL_RESOURCE_PATH
• The resource path is null

AI-assisted analysis of apache/dolphinscheduler@02eac45a1b (2026-09-06). Data as JSON: /api/errors/85b7f70a35f84e49. Report an issue: GitHub.