# files.upload Web API method sunset on 2025-11-12

- **Provider:** Slack
- **Endpoint:** `POST /api/files.upload`
- **Effective:** 2025-11-12
- **Severity:** critical
- **Change:** version-sunset
- **Status:** verified

## What changed

Slack deprecated files.upload. Apps created on or after 2024-05-16 could not use it, and Slack's reference page says the method stops working and is sunset on 2025-11-12 for existing apps too (the date was moved from 2025-03-11). Code that still uploads through files.upload fails with method_deprecated or deprecated_endpoint errors.

## What to do

Replace files.upload with the two-step flow: call files.getUploadURLExternal (filename, length) to get an upload_url and file_id, POST the file bytes to upload_url, then call files.completeUploadExternal with the file_id(s) and the channel_id, initial_comment or thread_ts you used to pass to files.upload. The official Slack SDKs wrap this as files_upload_v2 / filesUploadV2 / uploadV2.

## Sources

- Provider notice (2025-03-17): https://docs.slack.dev/changelog/2025/03/17/files-upload-extension
- https://docs.slack.dev/reference/methods/files.upload
- https://docs.slack.dev/changelog/2024-04-a-better-way-to-upload-files-is-here-to-stay

## Machine-readable

- Advisory: https://github.com/SriVarshini09/shapi-advisories/blob/main/advisories/slack-files-upload-retired.json
- OSV: https://shapi.dev/osv/slack-files-upload-retired.json