ChunkLoadError: Loading chunk XX failed (during add-on installation)

[willdurand]

There are a lot of errors like below since the last push.

https://sentry.prod.mozaws.net/operations/addons-frontend-amo-prod/issues/6015921/

ChunkLoadError: Loading chunk 49 failed.
(error: https://addons-amo.cdn.mozilla.net/amo-i18n-pl-5895ff0e3199834fe71a.js)
  at location (./src/locale/fr/amo.js?0bc5:7:1)
  at __webpack_require__ (./src/amo/components/LanguagePicker/index.js:36:28)
  at e/< (./src/amo/components/LanguagePicker/index.js:36:13)
  at G (./src/amo/utils/errors.js:14:14)
  at a (./src/amo/components/LanguagePicker/index.js:57:14)
...
(16 additional frame(s) were not displayed)

[kumar303]

Sentry suggests that these errors may be preventing add-on installation. Because of this and that 6.8K users are affected thus far, I'm marking it a P1.

[willdurand]

Sentry suggests that these errors may be preventing add-on installation. Because of this and that 6.8K users are affected thus far, I'm marking it a P1.

I tried clicking the install button but I cannot reproduce...

[willdurand]

We believe that the react-transition-group lib might be the problem. We merged an update in mozilla/addons-frontend#8226 and we found references of a SwitchTransition component in the Sentry logs. This lib has been updated in mozilla/addons-frontend#8241, after the tag. The update mentions the SwitchTransition component.

We think that updating the lib might fix this problem.

[kumar303]

We believe that the react-transition-group lib might be the problem.

Specifically, the stack traces begin with this:

There might be additional clues on what was fixed in 4.2.1 here: reactjs/react-transition-group#516

If upgrading to 4.2.1 doesn't stop the errors, we will try downgrading mozilla/addons-frontend#8226

[kumar303]

tag prepped for a hotfix: mozilla/addons-frontend@2019.07.04...2019.07.04-1

[willdurand]

The hotfix has been deployed in production but we're still seeing the same Sentry events 😞

[willdurand]

If upgrading to 4.2.1 doesn't stop the errors, we will try downgrading mozilla/addons-frontend#8226

I am going to try that in 2019.07.04-2, see: mozilla/addons-frontend@2019.07.04-1...2019.07.04-2

[ioanarusiczki]

@willdurand Had some errors at first on a new profile - FF67 unbranded - Win10 on stage which I can no longer reproduce now.

[willdurand]

I am going to try that in 2019.07.04-2, see: 2019.07.04-1...2019.07.04-2

We're still seeing the same Sentry events after the second hotfix has been deployed. I believe it has nothing to do with react-transition-group...

It could be caused by mozilla/addons-frontend@5c1cfa7, maybe.

[willdurand]

Maybe related threads:

• load chunks with xhr+eval rather than jsonp webpack/webpack#5630
• Uncaught (in promise) Error: Loading chunk # failed. webpack/webpack#7502 (comment)

[willdurand]

Sentry stats:

• Device: 61% are smartphone
• OS: 40% Windows 10, 24% Windows 7

Still, I cannot reproduce with a fresh Windows 10 + FF 67.