Something has broken an agent response with TTS for automation

Configuration
1

I am using an automation to get data and process back for agent response to then feed to tts.piper and play it on an Apple HomePod Mini. This worked until recently and I am running the latest everything but here is what I am getting in the errors:

Executed: April 28, 2026 at 6:30:04 AM
Error: ('failed to init decoder', -1)
Result:
params:
  domain: tts
  service: speak
  service_data:
    cache: false
    media_player_entity_id: media_player.great_room_2
    message: >-
      Today is Tuesday April 28, 2026. The weather is rainy across the area.
      Today's high temperature will be 76 degrees Fahrenheit and tonight's low
      temperature will be 63 degrees Fahrenheit. There is a chance of rain with
      a probability of 48 percent.
    options:
      voice: en_GB-alan-medium
    entity_id:
      - tts.piper
  target:
    entity_id:
      - tts.piper
running_script: false

Here is how I am calling this action:

action: tts.speak
metadata: {}
data:
  cache: false
  media_player_entity_id: media_player.great_room_2
  options:
    voice: en_GB-alan-medium
  message: "{{ agent.response.speech.plain.speech }}"
target:
  entity_id: tts.piper

Trying to figure out what the issue is and appreciate any insight. Thanks!

2

That says Piper failed to decode the message you sent - the problem is there. How do you have piper setup. Id check it’s log for more info…

3

I don’t think that is fully the issue as I do this fine with a sample action like this and it works on that same device.

Also piper has NO errors.

action: tts.speak
target:
  entity_id: tts.piper
data:
  cache: true
  media_player_entity_id: media_player.great_room_2
  message: Test
  options:
    voice: en_GB-alan-medium
4

I’m getting (‘failed to init decoder’, -1) on playing tts to HomePods on automations that were working for months as well. Started happening in the last week or so. I’m on ha os, core 2026.4.4. I’m pretty sure the issue started after that update with no changes. Similar issue to you where certain tts will work and other will fail. Hoping it’s just a bug that needs fixing. I may try to revert to an earlier version for testing if possible. I’ve not tried that before.

5

For what it’s worth I reverted back to 2026.4.3 and it is working fine again. I think there is some bug in 2026.4.4. Not sure if that’s the same for you but it may be worth a try. For HA OS from terminal I just did ha core update --version 2026.4.3, that did the downgrade.

6

For what it’s worth it’s still broken in. 2026.5.2.

7

Same issue here.

It took me a while to narrow it down. I use OpenAI to generate the message and Amazon Polly for the TTS. Depending on the target speaker, the message is sent to Google, Apple or Sonos devices.

Apple speakers recently started failing. After some debugging, I found that longer TTS messages fail on Apple/HomePod devices, while short messages still work correctly. Sending the exact same failing messages to Sonos works without any issue.

Conclusion: Apple HomePod/HomePod Mini devices no longer seem to accept longer TTS messages correctly.

Error:
(‘failed to init decoder’, -1)

Update:
Same issue with OpenAI TTS (which is quite nice btw). Longer messages on Apple Devices just doesn't work anymore.

8

Same error on my end when playing an .mp3 file to the HomePod Mini.

Action:

action: media_player.play_media
metadata: {}
target:
  entity_id: media_player.homepod_mini
data:
  media:
    media_content_id: media-source://media_source/local/greeting.mp3
    media_content_type: audio/mpeg
    metadata:
      title: greeting.mp3
      thumbnail: null
      media_class: music
      children_media_class: null
      navigateIds:
        - {}
        - media_content_type: app
          media_content_id: media-source://media_source
      browse_entity_id: media_player.homepod_mini

Error: Error: ('failed to init decoder', -1)

Running HA 2026.5.4
HomePod Mini version 26.5 (23L471)

Edit: FYI I downgraded to HA 2026.4.3 and it works again. Thanks @pjrage! Hope this gets fixed soon.

9

Just commenting to log I have this issue as well. Reported on the Github project page as well: Failed to perform the action media_player/play_media. ('failed to init decoder', -1 · Issue #169164 · home-assistant/core · GitHub. For my I'm trying to play an MP3 file to my HomePod mini. I have reverted back to 2026.4.1.