[Fine Uploader 5.16.2] Error when attempting to parse xhr response text (Unexpected token < in JSON at position 0)

[EwaMakowska]

Maybe someone can help me solve this error?

my configuration:

const uploaderConfig = {
	language: "en",
	itemLimit: 1,
	uploadFileUrl: 'http://localhost:8080/upload/',
	deleteFileUrl: 'http://localhost:8080/upload/',
	showMessage: (vue, message) => {
		console.log("???", vue, message);
		
		vue.$dlg.alert(message, {messageType: 'error'});
	}
}

            ....
            <v-uploader
              :multiple="true"
              buttonText="zmień avatar"
              @done="uploadDone"
            ></v-uploader>
            ....

               methods: {
                  uploadDone(files) {
                        if (files && Array.isArray(files) && files.length) {
                            console.log("????????//",files);
                         }
                    }
               },