nodejs firebase error RangeError: Maximum call stack size exceeded failure

I was facing the same error

Error:

Unhandled error RangeError: Maximum call stack size exceeded
    at Function.isNull (/srv/node_modules/lodash/lodash.js:11949:20)
    at encode (/srv/node_modules/firebase-functions/lib/providers/https.js:154:11)
    at /srv/node_modules/lodash/lodash.js:13401:38
    at /srv/node_modules/lodash/lodash.js:4905:15
    at baseForOwn (/srv/node_modules/lodash/lodash.js:2990:24)
    at Function.mapValues (/srv/node_modules/lodash/lodash.js:13400:7)
    at encode (/srv/node_modules/firebase-functions/lib/providers/https.js:179:18)
    at arrayMap (/srv/node_modules/lodash/lodash.js:639:23)
    at Function.map (/srv/node_modules/lodash/lodash.js:9554:14)
    at encode (/srv/node_modules/firebase-functions/lib/providers/https.js:173:18)

My callable function :

exports.addRequest = functions.https.onCall((data, context) => {
    return admin.firestore().collection('requests').add({
        text: data.text,
        upvotes: 0,
    });
}); 

I solved it by changing node package version in functions/package.json from 8 to 10 and it's working fine now.

You're updating the same node that you're reading. This causes the on("value" callback to be triggered again. Which in turn then writes a new value, which trigger the callback again. And that continues until the runtime runs out of call stack space.

The simplest solution is to use once() instead of on():

   var ref = database.ref('users');
    try{
        ref.orderByChild('username').equalTo(usrID).once("value", (snapshot)=> {
            if(!snapshot.val()){
                checker = true;
            }

            if(snapshot.val()){
                admin.database().ref('users/' + usrID + '/currentLocation').update({
                    lat: usrCoords.lat,
                    long: usrCoords.long
                });
                return res.json({msg: 'user coords changed', success: true});
            //  checker = false;
            }


            // res.json({msg: 'username is not in D.B', success: false});

        });
    }catch(ex){
         console.log('ex /updateCoords = '+ex);
    }