Common M3U8 Errors and Solutions
Use this guide to diagnose M3U8 playback, download, and conversion failures.
CORS cross-origin error
Error message
Access to XMLHttpRequest at 'https://example.com/video.m3u8'
from origin 'https://yoursite.com' has been blocked by CORS policy:
No 'Access-Control-Allow-Origin' header is present on the requested resource.Solutions
1. Configure CORS headers on the server
Add Access-Control-Allow-Origin for the domain that loads the M3U8 file.
2. Use a backend proxy
Fetch the playlist through your server when the source cannot expose browser CORS headers.
3. Use same-origin resources
Host the page, playlist, segments, and keys under the same origin when possible.
404 file not found
Error message
GET https://example.com/segment-1.ts 404 (Not Found)
Failed to fetch segment #1 of "https://example.com/playlist.m3u8"Solutions
1. Check URL paths
Confirm that TS or fMP4 segment paths in the M3U8 file are correct.
2. Verify files exist
Open the segment URL directly and confirm the server returns the media file.
3. Check the base URL
Relative segment paths must resolve against the real playlist location.
Decode or playback error
Error message
MEDIA_ERR_DECODE: The media resource indicated by the src attribute
or assigned media provider object was not suitable.
DOMException: Failed to decode media resourceSolutions
1. Check codecs
Use browser-compatible codecs such as H.264 video and AAC audio.
2. Validate M3U8 syntax
Confirm required tags such as #EXTM3U and #EXTINF are present and valid.
3. Use an HLS player
Use HLS.js or another dedicated player for better browser compatibility.
Network timeout or connection error
Error message
NetworkError: Failed to fetch
ERR_CONNECTION_TIMED_OUT
Manifest request timed outSolutions
1. Increase timeout settings
Give slow networks more time before declaring the playlist or segment failed.
2. Use CDN delivery
Serve segments through a CDN to reduce global latency and packet loss.
3. Add retry logic
Retry temporary playlist, segment, and key requests before failing playback.
Encrypted content error
Error message
KEY_LOAD_ERROR: Failed to load decryption key
KEY_SESSION_ERROR: Failed to generate license request
DECRYPT_ERROR: Failed to decrypt segmentSolutions
1. Verify the key URL
Make sure the URI in #EXT-X-KEY is reachable and returns the expected key.
2. Check key format
AES-128 keys should be 16 bytes and served without accidental text encoding changes.
3. Configure CORS for keys
The key server must allow the browser to request the key from the playback page.
Recommended debug tools
Browser DevTools
Check Network requests, response headers, status codes, and Console errors.
HLS.js Demo
Test a direct M3U8 URL in a known HLS player to isolate player issues.
FFmpeg/FFprobe
Inspect codecs, stream metadata, segment availability, and container details.
Online M3U8 validator
Validate playlist syntax against common HLS requirements.
Useful debug commands
Check video codec information
ffprobe -v quiet -print_format json -show_streams video.m3u8Test M3U8 URL reachability
curl -I https://example.com/video.m3u8Download and merge M3U8
ffmpeg -i "https://example.com/video.m3u8" -c copy output.mp4Try these resources: