Possible unhandled promise rejection, network error when using axios

Question

I'm trying to send JSON data using react-native, axios and Expo, but when I press "Send" on my application, I get this warning:

Possible unhandled promise rejection, Error: Network Error

My API is correctly receiving the notification (JSON) when I try to send it via POSTman, but when I try to send it using axios, I get the above warning message, so maybe react is not sending the data correctly.

export default class NotificationsInput extends React.Component {

state = {
    token: '',
    title: '',
    body: ''
}

handleToken = event => {
    this.setState({ token: event.target.value })
}

handleTitle = event => {
    this.setState({ title: event.target.value })
}

handleBody = event => {
    this.setState({ body: event.target.value })
}

handleSubmit = event => {
    event.preventDefault();

    let notification = JSON.stringify({
        token: this.state.token,
        title: this.state.title,
        body: this.state.body
    })

    let headers = {
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json'
        }

    }
    axios.post(`http://127.0.0.1:8000/send_push_message/`, notification, headers)
        .then(res => {
            console.log(res);
            console.log(res.data)
        })
        .then(error => console.log(error));

}

render() {
    return (
        <View>
            <TextInput onChange={this.handleToken}
                style={{ height: 25, width: 200, borderColor: 'black', borderWidth: 1 }}
            />
            <TextInput onChange={this.handleTitle}
                style={{ height: 40, width: 200, borderColor: 'black', borderWidth: 1 }}
            />
            <TextInput onChange={this.handleBody}
                style={{ height: 40, width: 200, borderColor: 'black', borderWidth: 1 }}
            />
            <Button onPress={this.handleSubmit} title="Send">Send</Button>
        </View>
    )
}

}

Edit :

I added the catch() function, but the error now is only Network Error in the console.

handleSubmit = event => {
    event.preventDefault();

    let notification = JSON.stringify({
        token: this.state.token,
        title: this.state.title,
        body: this.state.body
    })

    let headers = {
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json'
        }

    }
    axios.post(`http://127.0.0.1:8000/send_push_message/`, notification, headers)
    .then(res => {
        console.log(res);
        console.log(res.data)
    })
    .catch(error => console.log(error));

}

possible unhandled promise rejection (id: 0): Error: Network Error — Biel Borba, Sep 25 '18 at 04:28
your error suggests you are not handling the promise rejection which is to add `.catch` as mentioned by other users also check this :https://stackoverflow.com/questions/38842499/react-native-possible-unhandled-promise-rejection — aravind_reddy, Sep 25 '18 at 04:33
after adding the `.catch` block what is the error you are getting ? — aravind_reddy, Sep 25 '18 at 04:36
i think that i'm not sending correctly or the backend is not accepting, the console only shows "Network error" and some errors in node-modules — Biel Borba, Sep 25 '18 at 04:42
Possible duplicate of [React Native: Possible unhandled promise rejection](https://stackoverflow.com/questions/38842499/react-native-possible-unhandled-promise-rejection) — aravind_reddy, Sep 25 '18 at 04:43

score 4 · Answer 1 · answered Sep 25 '18 at 04:27

4

I can see you have chained two, .then which is not correct. You need a catch block to catch network errors. Take a look below

  axios.post(`http://127.0.0.1:8000/send_push_message/`, notification, headers)
    .then(res => {
        console.log(res);
        console.log(res.data)
    })
    .catch(error => console.log(error));

answered Sep 25 '18 at 04:27

Shubham Gupta

2,596
1
8
19

@Rik i meant in his piece of code. he was trying to catch err in .then – Shubham Gupta Sep 25 '18 at 04:30
1

i tried adding a catch, but this only make the error pop in my console – Biel Borba Sep 25 '18 at 04:31
@BielBorba that is correct which means your call is getting rejected from backend. I think it looking for some data in payload which it is not finding and failing. https://medium.com/@dtinth/making-unhandled-promise-rejections-crash-the-node-js-process-ffc27cfcc9dd – Shubham Gupta Sep 25 '18 at 04:35

score 1 · Answer 2 · answered Sep 25 '18 at 04:20

1

Use catch instead of then for error handling.

.catch(error => console.log(error));

answered Sep 25 '18 at 04:20

Rik

467
4
14

1

i tried, but i keep gettin the same error on the console – Biel Borba Sep 25 '18 at 04:23
1

Is CORS enabled on the backend? – Rik Sep 25 '18 at 04:27

score 1 · Answer 3 · edited Apr 03 '23 at 18:18

1

Solved. Changed:

return axios.get('http://localhost:3000/hello')

to:

return axios.get('http://10.0.0.2:3000/hello')

and it works. In Android emulator, the localhost refers its device.

https://github.com/facebook/react-native/issues/10404

edited Apr 03 '23 at 18:18

DaveL17

1,673
7
24
38

answered Mar 29 '23 at 06:35

janierrl

11
1

score 0 · Answer 4 · answered Dec 01 '22 at 14:36

0

If you have cors enabled in your backend stack,

then try replacing 127.0.0.1 with 10.0.2.2

Hope this helps.

answered Dec 01 '22 at 14:36

Mr Coolman

29
4

score 0 · Answer 5 · answered Mar 03 '23 at 19:44

0

Check again your api_url.

It should include 'http' or 'https'

answered Mar 03 '23 at 19:44

Tugay Tuna

11
3

Possible unhandled promise rejection, network error when using axios

5 Answers5