Live MPD declares no availabilityStartTime
Without this anchor a player cannot work out which segments exist yet.
What it means
A dynamic MPD must declare @availabilityStartTime, the wall-clock instant the presentation began. It is missing.
Why it matters
Every segment availability calculation in live DASH is derived forward from this anchor. Without it a player cannot tell which segment is current, so it either guesses — and 404s — or refuses to start.
How to fix it
- Add availabilityStartTime to <MPD> as an xs:dateTime in UTC, ending in Z.
- It should be the instant the presentation started, not the time the manifest was written.
Check your own stream
The free DASH validator runs this check on every analysis and links each finding straight back here.
Open the DASH validator →Frequently asked questions
- What does "Live MPD declares no availabilityStartTime" mean?
- A dynamic MPD must declare @availabilityStartTime, the wall-clock instant the presentation began. It is missing.
- Why does it matter?
- Every segment availability calculation in live DASH is derived forward from this anchor. Without it a player cannot tell which segment is current, so it either guesses — and 404s — or refuses to start.
- How do I fix it?
- 1. Add availabilityStartTime to <MPD> as an xs:dateTime in UTC, ending in Z. 2. It should be the instant the presentation started, not the time the manifest was written.
- How can I detect this automatically?
- Paste your MPEG-DASH streaming URL into StreamTest's free DASH validator. It runs this check on every analysis, flags the finding, and links straight back to this page — no sign-up required.
Related DASH checks
- DASH manifest has no UTCTiming elementA live MPD without UTCTiming forces players to trust the device clock, so any skew on the viewer’s machine becomes stalls or missing segments.
- DASH availabilityStartTime is in the futureThe manifest claims the presentation starts later than the current time, so no segment is available yet and playback cannot begin.
- The DASH manifest is not well-formed XMLThe document could not be parsed as XML, so nothing else could be checked.
- The document has no MPD root elementThe XML parsed, but its root is not <MPD>, so it is not a DASH manifest.
- MPD declares no profileWithout @profiles a player cannot tell which DASH feature set the manifest expects.
- MPD declares no minBufferTimePlayers use this required attribute to size the initial buffer before starting playback.