1511640 - Snippets fail to load with "JSON.parse: unexpected end of data at line 1 column 1 of the JSON data"

Status: RESOLVED WONTFIX

(Firefox :: Messaging System, defect, P2)

Description

[Dão Gottwald [:dao]]

Since yesterday I don't get snippets in about:newtab anymore, and there's this message in the browser console:

JSON.parse: unexpected end of data at line 1 column 1 of the JSON data
  _remoteLoader resource://activity-stream/lib/ASRouter.jsm:134
  throw self-hosted:1227

I'm using Nightly on Windows 10.

Comment 1

[Giorgos Logiotatidis [:giorgos]]

Thanks for filing ::dao. This looks like an Activity Stream problem.

Comment 2

[Ian Bicking (:ianbicking)]

Dao, are you still seeing this issue? My assumption is that there's some ops issue that is causing the snippets endpoint to return no data (despite a 200 OK response code). A hiccup in the service doesn't seem particularly concerning, assuming that it's not persistent.

If it resolved, I'll propose that we fall back to a cached snippet when we get an empty response (which is what the code does for other kinds of failures). If it's not resolved, then we have to figure out why the endpoint isn't returning any data.

Comment 3

[Giorgos Logiotatidis [:giorgos]]

The snippets endpoint may return no data because there are no snippets for the release / locale / build combination to return.

We used to return 204 - Empty Response but AS couldn't handle that initially (see bug 1428274), so we changed that to 200.

If the service returns no content, thus no snippets, no snippets should be displayed.

I read the code in AS [0] and I'm not sure whether AS will store and cache an empty array for a 204 response.

Anyways I filed an issue [1] in the snippets service to make it always return json valid responses. 

[0] https://github.com/mozilla/activity-stream/blob/f40d201cfe4d67fec4ba7adc10d46c4c97924af6/lib/ASRouter.jsm#L108
[1] https://github.com/mozmeao/snippets-service/issues/888

Comment 4

[Dão Gottwald [:dao]]

(In reply to Ian Bicking (:ianbicking) from comment #2)
> Dao, are you still seeing this issue?

Getting neither snippets nor the error message at the moment.

Comment 5

[Ian Bicking (:ianbicking)]

I'm going to WONTFIX this, as the actual behavior is correct/intentional: when we get a 200 response with no body from the server, then no snippets are displayed. The only problem is the error message in browser console.

The snippets bug (https://github.com/mozmeao/snippets-service/issues/888) is fixed, and so this error shouldn't occur once that change is deployed.