Shopify app install received an error response (400 Bad Request)

Shopify Apps

Topic summary

Issue: A 400 Bad Request occurs when a single merchant attempts to install a Shopify app; other merchants install successfully.

Troubleshooting steps suggested by support:

  • Try a different browser or a Chrome Incognito window.
  • Clear browser cache and cookies.
  • Ensure cookies aren’t blocked (especially third‑party cookies) and no Shopify URLs are blocked in settings.
  • Share the specific app details with support if the issue persists.

Additional technical insight:

  • The App Proxy subpath (the URL path Shopify proxies to the app) cannot be changed for existing installs. Changing it in the Partners App Dashboard only affects new installs.
  • If the subpath was briefly altered when the affected merchant installed, their install may be tied to the old subpath.
  • Practical fix: uninstall and reinstall the app for that merchant.

Status: No confirmed resolution yet. Next steps are to apply browser/cookie fixes, then verify App Proxy subpath history and reinstall if needed.

Summarized with AI on December 16. AI used: gpt-5.
1

I’ve received
Received an error response (400 Bad Request) from Shopify for one of merchant try to install our app published in app store.

However app is working correctly for other merchants this issue occurs specific to one user only.

Help me out with this and let me know if you need more information regarding this.

2

Hi @troopstech23

Thanks for letting us know about the troubles you’re running into with accessing apps. When this error appears, there are a few different troubleshooting steps that I recommend working through to reach a resolution. Please see these outlined below:

1. Using a different browser.

In most cases, using a different browser can help resolve this. Safari and Firefox are both great options to consider for an alternative to Google Chrome. However, using an Incognito window in Chrome is also another method that can be useful.

2. Clear the cache and cookies on your browser.

Clearing this data can sometimes remove errors like the one you’re experiencing. To clear the cache and cookies on Chrome, just follow these steps. Equally, the steps to do this on Firefox can be found here, and Safari’s steps are outlined here.

3. Unblock cookies.

Cookies being blocked is a common issue on Chrome, but may also occur on Safari, too. When this happens, errors like the one you’re experiencing can appear and create frustration. With this in mind, it’s typically best to unblock the cookies on the browser you’re using.

To do this on Chrome, please follow these steps:

  1. Enter “chrome://settings/content/cookies” in your browser’s URL bar and hit “enter”.
  2. Then, make sure the “Block third-party cookies” option is disabled, and no other Shopify URLs are showing in the blocked settings.

On Safari, follow these steps:

  1. Click “Safari” in your browser’s menu.
  2. Click “Preferences” and select “Privacy”.
  3. Under “Cookies and website data” ensure “Block all cookies” is not selected.

Following this troubleshooting should resolve the issue you’re experiencing, but if you’re still having troubles please let me know which app you’re seeing this error on, and I’ll be glad to assist further!

3

I don’t know if it’s relevant to your specific testing, but I discovered today that the App Proxy subpath cannot be updated for existing installations of the app. Once you install an app, you lock the subpath of the app proxy, meaning that if you then change that in the Partners App Dashboard, it only works for new installs.

I wonder if the subpath was set to a different value briefly (when your one problem merchant installed the app) then reverted?

Sadly, the only way I’ve found to fix it is to uninstall and reinstall for the merchant experiencing the problem.