Synthesistranscript endpoint returning ERR_NETWORK in West Europe (Speech Studio)*

synthesistranscript endpoint returning ERR_NETWORK in West Europe (Speech Studio)

When attempting to upload a data segment as a Transcript (automatic audio synthesis) dataset type in Azure Speech Studio, the upload fails every time with a network error. All other dataset types (e.g. Plain Text) upload successfully to the same project.

Region: West Europe

Resource type: SpeechServices (S0)

Affected endpoint: https://westeurope.data.api.speech.microsoft.com/v1.0/projects/{project-id}/synthesistranscript

Error:

Failed to upload data segment_transcript. Error: {

  "message": "Network Error",

  "name": "AxiosError",

  "code": "ERR_NETWORK",

  "config": {

    "method": "post",

    "url": "https://westeurope.data.api.speech.microsoft.com/v1.0/projects/.../synthesistranscript",

    "axios-retry": {

      "retries": 4,

      "retryCount": 4

    }

  }

}

The request is retried 4 times by the Studio UI and fails each time with no HTTP status code returned — the connection appears to be dropped before a response is received.

What I've tried:

• Uploading the same file as Plain Text — succeeds immediately
• Retrying multiple times over several hours — same result
• Different browser sessions

This has occurred across multiple separate projects in the same West Europe resource. The synthesistranscript endpoint specifically appears to be unavailable or unstable in this region. No incident is currently listed on status.azure.com.

Has anyone else hit this recently, or can Microsoft confirm whether there is a known issue with the synthesis transcript upload endpoint in West Europe? As far as I know this has been an issue since July 24th. I have also noticed uploading data and training has been taking much longer than usually, is this a West Europe capacity issue. Please kindly advise. Thank you!