[Sentry] Error: Fetch failed with status '403': ''

[sentry-io]

Sentry Issue: METAMASK-PVS3

Error: Fetch failed with status '403': ''
  at _default (shared/lib/fetch-with-cache.js:42:11)
  at checkTokenDetection (ui/components/ui/new-network-info/new-network-info.js:51:40)
  at checkTokenDetection (ui/components/ui/new-network-info/new-network-info.js:60:11)

403 errors are expected in small numbers. If they occur in large numbers, it may be due to an improper security mechanism we added server side. So if we see a spike in 403s, we should throw an alert so we catch the error state.

Next step:

• Send an analytics event to Segment when 403 happens instead of throwing an error that ends up in Sentry. This will reduce unnecessary noise in Sentry (Sentry is meant to be used only for unexpected errors).

[gauthierpetetin]

Events in past 14 days: 327

[gauthierpetetin]

A 403 status typically indicates a "Forbidden" response, suggesting that MetaMask does not have permission to access a particular resource or endpoint.
The subsequent message, "Failed to fetch Swaps feature flags and Swaps liveness, defaulting to false.", indicates that because the fetch failed, the feature flags for "Swaps" were set to false by default.

[danjm]

This error seems to be tracking not just 403 failures, but any failed requests in fetch--with-cache that don't meet the if (!response.ok) { condition

It seems there are cases where fetchWithCache is called from ui/components/ui/new-network-info/new-network-info.js and it can fail with a 403

There are other cases where fetchWithCache is called from ui/pages/swaps/swaps.util.ts and it can fail with a 422

Another is ui/pages/swaps/swaps.util.ts in a.fetchTopAssets

Another is ui/pages/swaps/swaps.util.ts in a.fetchAggregatorMetadata

As a solution to this problem, we could look at each place that fetchWithCache is called, and add specific handling for 403, 422 and 429 errors.

[DDDDDanica]

After having a chat with @gauthierpetetin we would like to solve this issue in following way:
1- trace the issue to see if there’s a way to fix for each error code
eg: 502 is caused by language missing in some locales
Private Zenhub Image

2- improve the error message to log better:
eg: Fetch with cache failed within function 'getIsTokenDetectionSupported' with status '502':