App Proxy Don't Work / "There was an error in the third-party application" Issue

[jem_punsalan]

Recently we get this Internal Server Error 500 Indicating the following message:

I checked all throughout the community support and we only have two topics related to this one:

https://community.shopify.com/c/Shopify-Apps/App-proxy-don-t-work-with-500-internal-server-error/m-p...

https://community.shopify.com/c/Shopify-APIs-SDKs/Application-Proxy-There-was-an-error-in-the-third-...

Anyway, this is the request header:

GET https://cs-testing-tg.myshopify.com/apps/dynamic/product/2139626831941?persona_label=&section_id=pro... HTTP/1.1
Accept: text/html, application/xhtml+xml, image/jxr, */*
Accept-Language: en-PH
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko
Accept-Encoding: gzip, deflate
Host: cs-testing-tg.myshopify.com
Connection: Keep-Alive
Cookie: _shopify_fs=2019-06-26T06%3A59%3A24.490Z; _shopify_y=9f2bd781-4ef6-4bca-9b0b-37b8fa0300a1; _y=9f2bd781-4ef6-4bca-9b0b-37b8fa0300a1; __cfduid=d52b5bdc79e14fef5cf3f458dea231d251561532363; _landing_page=%2Fapps%2Fdynamic%2Fproduct%2F2139626831941%3Fpersona_label%3D%26section_id%3Dproduct-template%26section_settings%255Bimage_size%255D%3Dmedium%26section_settings%255Bshow_quantity_selector%255D%3Dfalse%26section_settings%255Bshow_variant_labels%255D%3Dtrue%26section_settings%255Bshow_vendor%255D%3Dfalse%26section_settings%255Benable_zoom%255D%3Dtrue%26section_settings%255Bshow_share_buttons%255D%3Dtrue%26section_settings%255Bshow_contextualized_title%255D%3Dtrue%26section_settings%255Bshow_contextualized_image%255D%3Dtrue%26section_settings%255Bshow_contextualized_desc%255D%3Dtrue%26section_settings%255Bshow_contextualized_text_asset%255D%3Dtrue%26section_settings%255Bshow_upsell_crossell_products%255D%3Dtrue%26affinityTags%3D; _shopify_fs=2019-06-26T06%3A59%3A24.490Z; cart_sig=; _shopify_y=9f2bd781-4ef6-4bca-9b0b-37b8fa0300a1; _orig_referrer=; _y=9f2bd781-4ef6-4bca-9b0b-37b8fa0300a1; secure_customer_sig=

and this is the response header:

HTTP/1.1 500 Internal Server Error
Date: Wed, 26 Jun 2019 13:39:19 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Set-Cookie: secure_customer_sig=; path=/; expires=Sun, 26 Jun 2039 13:39:19 -0000; secure; HttpOnly
Set-Cookie: cart_sig=; path=/; expires=Wed, 10 Jul 2019 13:39:19 -0000; HttpOnly
Content-Security-Policy: block-all-mixed-content; frame-ancestors 'none'; upgrade-insecure-requests; report-uri /csp-report?source%5Baction%5D=app_liquid&source%5Bapp%5D=Shopify&source%5Bcontroller%5D=storefront_section%2Fapp_proxy&source%5Bsection%5D=storefront&source%5Buuid%5D=90ff8933-ea2a-4589-8db7-653991419c2c
Vary: Accept-Encoding
X-Dc: gcp-us-central1,gcp-us-central1,gcp-us-east1
X-Sorting-Hat-ShopId: 3784638533
X-ShardId: 68
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-Download-Options: noopen
X-ShopId: 3784638533
X-Shopify-Stage: production
X-XSS-Protection: 1; mode=block; report=/xss-report?source%5Baction%5D=app_liquid&source%5Bapp%5D=Shopify&source%5Bcontroller%5D=storefront_section%2Fapp_proxy&source%5Bsection%5D=storefront&source%5Buuid%5D=90ff8933-ea2a-4589-8db7-653991419c2c
X-Permitted-Cross-Domain-Policies: none
X-Request-Id: 90ff8933-ea2a-4589-8db7-653991419c2c
Strict-Transport-Security: max-age=7889238
X-Sorting-Hat-PodId: 68
Content-Language: en
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
Server: cloudflare
CF-RAY: 4ecf9625e9a8a928-SIN
Content-Length: 28891

Please help on this as we cant move with our development and testing due to this issue. If theres anything we need to do on our end, kindly let us know. Thank you!

[Busfox]

Hi @jem_punsalan,

The error you are seeing will come up when there's an error with the app page you are trying to embed on the storefront proxy page. Based on this, it's difficult for me to help, aside from giving you some anecdotal suggestion from past cases of this error.

Two things come to mind that I'd recommend trying. The first is, pass the proper content-type header in your proxy page. The content-type you want is application/liquid.

Similarly, I've seen apps have issues when they do not specify a content-length header value in their request.

Can you try adding these request headers and let me know if you continue to have trouble?

Cheers,