Apple App Site Association File Download Error

We are trying to add universal link functionality to our app and currently trying to test this in one of our test environments.


We are currently seeing issues with the download of the file to the device but the console log entry doesn't give us much to go on:


### Download URL 'https://our.test.domain.com/.well-known/apple-app-site-association' failed: -6756/0xFFFFE59C kTypeErr


Can anyone help with understanding what is going wrong with the download?


We're aware that Apple have an on-line tool for validating the structure of this file but because our test environment is behind a firewall then the tool can't get to the file, this leads to two additional questions:


Does anyone know the IP range we would have to allow through for this tool to work?

Is anyone aware of a tool that will validate the structure of the file by uploading the file contents rather than pointing it at the URL of the file?


Thanks.

I have the same problem with my app since I mix new AASA iOS 13 format with old AASA format. It works on iOS 13, breaks on iOS 12 with the following console error log :

Code Block
### Download URL 'https://***/.well-known/apple-app-site-association' failed: -6756/0xFFFFE59C kTypeErr


Apple App Site Association File Download Error
 
 
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