# Multi Output Callback Incorrect Type

**URL:** <https://community.plotly.com/t/multi-output-callback-incorrect-type/22741>\
**Category:** Dash Python\
**Created:** [April 25, 2019, 11:42pm UTC](https://community.plotly.com/t/multi-output-callback-incorrect-type/22741 "2019-04-25T23:42:30Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![FewPeach](https://avatars.discourse-cdn.com/v4/letter/f/3e96dc/32.png) [@FewPeach](https://community.plotly.com/u/FewPeach)\
**Post date:** [April 25, 2019, 11:42pm UTC](https://community.plotly.com/t/multi-output-callback-incorrect-type/22741/1 "2019-04-25T23:42:30Z")

</div>

While working on my own app I ran into an IncorrectTypeException at my multi output callback. Single output worked just fine. Out of curiosity I also ran the example code from Getting Started Part 2, which then threw had the same problem. I have included the example code as I have copied it, since that is something that shouldn’t have stupid errors. I am using 42.0 and running with jupyter notebook.

```auto
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash( __name__ , external_stylesheets=external_stylesheets)

app.layout = html.Div([
    dcc.Input(
        id='num',
        type='number',
        value=5
    ),
    html.Table([
        html.Tr([html.Td(['x', html.Sup(2)]), html.Td(id='square')]),
        html.Tr([html.Td(['x', html.Sup(3)]), html.Td(id='cube')]),
        html.Tr([html.Td([2, html.Sup('x')]), html.Td(id='twos')]),
        html.Tr([html.Td([3, html.Sup('x')]), html.Td(id='threes')]),
        html.Tr([html.Td(['x', html.Sup('x')]), html.Td(id='x^x')]),
    ]),
])

@app.callback(
    [Output('square', 'children'),
     Output('cube', 'children'),
     Output('twos', 'children'),
     Output('threes', 'children'),
     Output('x^x', 'children')],
    [Input('num', 'value')])
def callback_a(x):
    return x **2, x** 3, 2 **x, 3** x, x**x

if __name__ == ' __main__':
    app.run_server(debug=True)

```

IncorrectTypeException Traceback (most recent call last)  
 in   
30 Output(‘threes’, ‘children’),  
31 Output(‘x^x’, ‘children’)],  
—\> 32 [Input(‘num’, ‘value’)])  
33 def callback\_a(x):  
34 return x **2, x** 3, 2 **x, 3** x, x\*\*x

…appdata\local\programs\python\python37\lib\site-packages\dash\dash.py in callback(self, output, inputs, state)  
877 any([isinstance(val, x) for x in valid]) or  
878 type(val). **name** == ‘unicode’  
–\> 879 )  
880  
881 def \_validate\_value(val, index=None):

…appdata\local\programs\python\python37\lib\site-packages\dash\dash.py in \_validate\_callback(self, output, inputs, state)  
667 ‘Same output was used in a’  
668 ’ multi output callback!\n Duplicates:\n {}’.format(  
–\> 669 ‘,\n’.join(  
670 k for k, v in  
671 ((str(x), output.count(x)) for x in output)

IncorrectTypeException: The output argument `[<dash.dependencies.Output object at 0x00000213C48C4E48>, <dash.dependencies.Output object at 0x00000213C49A2DA0>, <dash.dependencies.Output object at 0x00000213C49A2908>, <dash.dependencies.Output object at 0x00000213C49A2F98>, <dash.dependencies.Output object at 0x00000213C49A2668>]` is not of type `dash.Output`.

Any help would be greatly appreciated.

---

<div class="post-metadata">

**Author:** ![collerek](https://avatars.discourse-cdn.com/v4/letter/c/9f8e36/32.png) [@collerek](https://community.plotly.com/u/collerek)\
**Post date:** [April 26, 2019, 4:11pm UTC](https://community.plotly.com/t/multi-output-callback-incorrect-type/22741/2 "2019-04-26T16:11:10Z")

</div>

Hi, for me your example is working perfectly fine. Are you sure you updated all dependencies with dash and don’t have other callbacks that has the same outputs?