HumanSignal/label-studio · error · ValidationError

Maximum total size of all files is {settings.TASKS_MAX_FILE_

Error message

Maximum total size of all files is {settings.TASKS_MAX_FILE_SIZE} bytes, current size is {value} bytes

What it means

ValidationError raised by check_tasks_max_file_size in label_studio/data_import/uploader.py. Label Studio caps the combined size of all uploaded files per import request at settings.TASKS_MAX_FILE_SIZE (default 100 MB). When the computed total (sum of file.size, or a Content-Length header) is >= the limit, the import is rejected before download/processing.

Source

Thrown at label_studio/data_import/uploader.py:54

    num_columns = len(line.split(b',' if isinstance(line, bytes) else ','))
    for i in range(num_columns):
        names.append('column' + str(i + 1))
    file.seek(0)
    return names


def check_max_task_number(tasks):
    # max tasks
    if len(tasks) > settings.TASKS_MAX_NUMBER:
        raise ValidationError(
            f'Maximum task number is {settings.TASKS_MAX_NUMBER}, current task number is {len(tasks)}'
        )


def check_tasks_max_file_size(value):
    if value >= settings.TASKS_MAX_FILE_SIZE:
        raise ValidationError(
            f'Maximum total size of all files is {settings.TASKS_MAX_FILE_SIZE} bytes, current size is {value} bytes'
        )


def check_extensions(files):
    for filename, file_obj in files.items():
        _, ext = os.path.splitext(file_obj.name)
        if ext.lower() not in settings.SUPPORTED_EXTENSIONS:
            raise ValidationError(f'{ext} extension is not supported')


def check_request_files_size(files):
    total = sum([file.size for _, file in files.items()])

    check_tasks_max_file_size(total)


def create_file_upload(user, project, file):

View on GitHub (pinned to 0b49e9b539)

Solutions

Split the upload into multiple smaller files / requests, each under TASKS_MAX_FILE_SIZE (default 100 MB).
Increase the limit via the TASKS_MAX_FILE_SIZE env var (or settings) and restart Label Studio.
Compress or trim the input data (e.g. keep only needed columns) before importing.
For URL imports, serve/point to a file below the limit or use storage synchronization instead of direct download.

Example fix

// before
const fd = new FormData();
fd.append('file', hugeFile); // 300MB

// after: chunk into <100MB pieces and import sequentially
const CHUNK = 90 * 1024 * 1024;
for (const part of sliceFile(hugeFile, CHUNK)) await importOne(part);

Defensive patterns

Strategy: validation

Validate before calling

import os
MAX = int(os.environ.get('TASKS_MAX_FILE_SIZE', 104857600))
total = sum(f.size for f in files)
if total >= MAX:
    raise ValueError(f'Upload total {total} bytes >= limit {MAX}; split or raise TASKS_MAX_FILE_SIZE')

Try / catch

try:
    upload_files(files)
except ValidationError as e:
    if 'Maximum total size of all files' in str(e):
        for chunk in chunk_files(files, MAX // 2):
            upload_files(chunk)
    else:
        raise

Prevention

Sum file sizes client-side and compare to TASKS_MAX_FILE_SIZE before upload.
Chunk large uploads into pieces well under the limit (e.g. 90MB).
For URL imports, check the Content-Length header first before handing the URL to the API.
Keep the limit setting documented for users of your Label Studio instance.

When it happens

Trigger: check_request_files_size summing uploaded file sizes to >= TASKS_MAX_FILE_SIZE, or tasks_from_url reading a Content-Length header >= the limit before downloading a URL import.

Common situations: Uploading one huge CSV/JSON dump; multi-file upload where the combined size crosses the cap; URL import pointing at a large file; operator lowered TASKS_MAX_FILE_SIZE without telling users.

Related errors

AI-assisted analysis of HumanSignal/label-studio@0b49e9b539 (2026-08-29). Data as JSON: /api/errors/7d7181bf0cd50425. Report an issue: GitHub.