Increased 500 errors after 2019.02.14-2 release

Describe the problem and steps to reproduce it:

We have seen increased 500 errors after 2019.02.14-2 release. Please see the sceenshot below:

Even thought the absolute rate (<0.06 per second) seems to be low, but it is considered 3 times more than before. So unless something has changed and this is expected, this much increase is definitely an indication of some issue.

What happened?

We are not sure yet. Operation conditions haven’t changed for this release. And the increase of 500 happened immediate after the push finishes (judging by the time on the screenshot).

The disco-recommendations waffle was enabled for this release, but not sure it’s related or not.

What did you expect to happen?

If the increase of 500 is not expected due to some code changes, we should probably figure out a way to reduce it to its normal level.

Anything else we should know?

n/a

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For QA: please make sure “not found” pages are displayed correctly for the following locales:

• de
• en-US
• pt-BR

Not found pages are the ones that are displayed for an unknown add-on for instance (or a random url for a page that does not exist).

[kumar303]

Could you add some steps for QA? I think it’s just a matter of checking for regressions in some localizations.

[kumar303]

To recap, the quick fix preventing 500s landed in https://github.com/mozilla/addons-frontend/pull/7598

The next step is to try and come up with a way to prevent this kind of localization problem from occurring again.