AASA File for App Clip Stopped Working

Hello,

 We release an App Clip back in December 2020, and everything was working just fine for the longest time. However, sometime relatively recently, not exactly sure when it started, the Domain URL Status started showing this “Cannot Reach AASA File” error; and consequently, the App Clip invocation fails now.  

The API Validation Tool is saying “Error cannot parse app site association file” as the reason.  

We have not made any changes in the App / App Clip, and the associated domain is still set as appclips:mobileapp.caesars.com    

The Apple App Site Association file hasn’t been changed either, and the format still matches that specified on https://developer.apple.com/documentation/app_clips/associating_your_app_clip_with_your_website.

The AASA file returns no problem in a browser and from curl command as you can see below:

Last login: Tue Jul 12 09:11:11 on console

curl -v https://mobileapp.caesars.com/.well-known/apple-app-site-association
*  Trying 192.230.66.155:443...
* Connected to mobileapp.caesars.com (192.230.66.155) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
* CAfile: /etc/ssl/cert.pem
* CApath: none
* (304) (OUT), TLS handshake, Client hello (1):
* (304) (IN), TLS handshake, Server hello (2):
* (304) (IN), TLS handshake, Unknown (8):
* (304) (IN), TLS handshake, Certificate (11):
* (304) (IN), TLS handshake, CERT verify (15):
* (304) (IN), TLS handshake, Finished (20):
* (304) (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / AEAD-AES128-GCM-SHA256
* ALPN, server accepted to use h2
* Server certificate:
* subject: C=US; ST=Nevada; L=Las Vegas; O=Caesars License Company, LLC; CN=*.caesars.com
* start date: Jul 28 00:00:00 2020 GMT
* expire date: Oct 14 12:00:00 2022 GMT
* subjectAltName: host "mobileapp.caesars.com" matched cert's "*.caesars.com"
* issuer: C=US; O=DigiCert Inc; CN=DigiCert SHA2 Secure Server CA
* SSL certificate verify ok.
* Using HTTP2, server supports multiplexing
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x12b810400)
> GET /.well-known/apple-app-site-association HTTP/2
> Host: mobileapp.caesars.com
> user-agent: curl/7.79.1
> accept: */*
> 
* Connection state changed (MAX_CONCURRENT_STREAMS == 128)!
< HTTP/2 200 
< content-type: application/json
< last-modified: Tue, 29 Mar 2022 17:01:12 GMT
< accept-ranges: bytes
< etag: "8fb84c988e43d81:0"
< server: Microsoft-IIS/10.0
< x-powered-by: ASP.NET
< p3p: CP="DEVa TAIa CURa STA NAV COM PUR ADMa IND OUR CONa"
< date: Tue, 12 Jul 2022 14:13:38 GMT
< content-length: 94
< set-cookie: TLTUID=14DC54AD87C0CE8FE7D996B6462E29DA; Domain=caesars.com; Expires=Sun, 03-Mar-2024 14:13:38 GMT; Path=/
< set-cookie: TLTSID=CE56628D3C96FCC7119B576D984C3119; Domain=caesars.com; Path=/
< set-cookie: visid_incap_2158031=HUn4aDqCSo+WP67o1FH52pGBzWIAAAAAQUIPAAAAAAB3XfZ+ShjpzS05c/MsxAjO; expires=Wed, 12 Jul 2023 06:18:20 GMT; HttpOnly; path=/; Domain=.caesars.com
< set-cookie: nlbi_2158031=q84xFZbqUDGbu15TtwLJSwAAAABBaYw0KJNNHWaeJ2p5/DNV; path=/; Domain=.caesars.com
< set-cookie: incap_ses_979_2158031=w4MXYaAK4R7YuhVx/BuWDZGBzWIAAAAA8Dt1Yyj9qc8nFNp3F96Kxg==; path=/; Domain=.caesars.com
< x-cdn: Imperva
< x-iinfo: 11-18630097-18630107 NNNY CT(35 74 0) RT(1657635217346 57) q(0 0 0 1) r(0 0) U12
< 
{
 "appclips": {
  "apps": [
   "YXFZ76LPGW.com.caesars.playbytr.Clip"
  ]
 }
* Connection #0 to host mobileapp.caesars.com left intact

Again, this was all working without any problems and just suddenly stopped for some reason without any apparent explanation. I’ve looked at similar issues reported in the forums with no luck helping solve this issue yet. Any guidance/help would be greatly appreciated!