Firebase Functions: Unclear "connection error" - firebase

Question

I am getting this error every so many runs with my HTTP Firebase Cloud Function:
Function execution took ****ms, finished with status: 'connection error'
It happens inconsistently but I can't quite narrow down what the problem is. I don't believe the error is in my app as it's not showing an error printout. And my own connection with firebase while running this cloud function isn't cutting out.
Any ideas why Firebase randomly fails cloud function executions with "connection error"?

Answer 1

Function execution took ****ms, finished with status: 'connection error' or ECONNRESET usually happens when a function doesn’t know whether a promise resolved or not.
Every promise must be returned, as mentioned in the docs here. There is also a blog post (with helpful video!) about this.
A couple of examples of unreturned promises:
exports.someFunc = functions.database.ref('/some/path').onCreate(event => {
let db = admin.database();
// UNRETURNED PROMISE
db.ref('/some/path').remove();
return db.ref('/some/other/path').set(event.data.val());
});
exports.makeUppercase = functions.database.ref('/hello/{pushId}').onWrite(event => {
return event.data.ref.set('world').then(snap => {
// UNRETURNED PROMISE
admin.database().ref('lastwrite').set(admin.database.ServerValue.TIMESTAMP);
});
});
exports.makeUppercase = functions.database.ref('/hello/{pushId}').onWrite(event => {
// UNRETURNED PROMISE
event.data.ref.set('world').then(snap => {
return admin.database().ref('lastwrite').set(admin.database.ServerValue.TIMESTAMP);
});
});
To help catch this mistake before deploying code, check out this eslint rule.
For an in-depth look at promises, here are some helpful resources:
Mozilla docs
Ponyfoo promises deep dive
Links to the ECMA standard
Egghead.io course

Answer 2

Even though this question has an approved answer, you may have followed the steps in that answer and still reached a point where the error was still occurring.
In that case, we were informed by GCP that there's a known issue with Node 8 CFs and this connection error, for which the workaround is to update the node version to 10.
Related github issue: https://github.com/firebase/firebase-functions/issues/429
Specific comment: https://github.com/firebase/firebase-functions/issues/429#issuecomment-577324193

Answer 3

I think it might be too many simultaneous firebase database connections :/ https://groups.google.com/forum/#!topic/firebase-talk/4RjyYIDqMVQ

Answer 4

I faced the same issue while deploying uninstallTracking event to firebase for android device,
Turns out that the property I was trying to access was available for only some users ,
So when it couldn't find the property for those other users it gives this error
So first just check the property you are trying to access is there or not

Answer 5

I've been getting this on an HTTP trigger that immediately calls response.end() with no other code!
I had a very complex function that was working great then it stopped working due to this error. I tried for hours playing with my code until there was nothing left but a response.end() and still the error persisted.
I found that by deleting the trigger (deploying my triggers with the offending trigger commented out), then deploying again with the trigger uncommented seems to have fixed it.
Perhaps there is a bug that works in that gets reset when you delete the trigger in the cloud.
Hope this saves somebody some frustration.

Answer 6

it could be outdated libraries.
go to terminal
inside functions folder write command
npm outdated
this will show all libraries to require to be updated.
To update libraries write command
npm update
deploy cloud functions with
firebase deploy --only functions

Answer 7

For debugging purposes, I did the following:
response.send(someArray.length)
...which resulted in the following:
response.send(218)
...which resulted in a bodyless response, just a "status code" (namely 218) being sent. To fix this, I did:
response.send("count: " + someArray.length)