Uppy doesn't propogate Cross-Origin error

If I try and use a S3-presigned-URL to PUT a file and the CORS configuration is not correct, i.e. PUT isn’t allowed, no appropriate error message is sent to the upload-error callback. This means I can’t let the user know what went wrong.

E.g.

this._uppy.on('upload-error', this._uppyError);

private readonly _uppyError: Function = (_file: any, error: Error, response: any) => {
    // response is undefined
    // error contains the text 'Upload error'
};

These values were sent by the error Event-Handler:

var error = buildResponseError(xhr, opts.getResponseError(xhr.responseText, xhr));

_this3.uppy.emit('upload-error', file, error);

xhr is:

mozAnon: false
mozSystem: false
onabort: null
onerror: null
onload: null
onloadend: null
onloadstart: null
onprogress: null
onreadystatechange: null
ontimeout: null
readyState: 4
response: ""
responseText: ""
responseType: "text"
responseURL: ""
status: 0
statusText: ""
timeout: 0
upload: XMLHttpRequestUpload
withCredentials: false

In the logs I receive the following two error messages:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://s3.eu-central-1.amazonaws.com/[omitted]. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://s3.eu-central-1.amazonaws.com/[omitted]. (Reason: CORS request did not succeed).

As far as I can tell, this doesn’t work as it should, but maybe there is an alternative way of getting at the error?

[Druckles]

It might have taken a while, but I’ve confirmed that this now works: we can ignore the request object and simply read out what’s in error.message, if it’s present, which is:

This looks like a network error, the endpoint might be blocked by an internet provider or a firewall. Source error: [Error: Upload error]

As that’s all we can get from the browser, it’ll have to do and if necessary we can check in the client’s browser logs 😃

[Druckles]

Ah, that’s great. We don’t have the latest version yet so I’ll have a check to see if that’s any better. Thank you!