“KeyError: “Callback function not found for output…” missing @?

Dash Python
1

I am trying to run a callback based on a button click but get KeyError: “Callback function not found for output ‘…EEp_msg.children…EEp_table.data…’, perhaps you forgot to prepend the ‘@’?”
What I am trying to do take input from a dropdown, and two input field, upon clicking the ‘ADD’ button, it will make changes in three output components. 1) shows a string message, 2) update the data property of a Dash-table, 3) update a figure.
I could not able to make it works.
Note: I am using Dash proxy app
from dash_extensions.enrich import DashProxy, MultiplexerTransform
app = DashProxy(prevent_initial_callbacks=True, transforms=[MultiplexerTransform()])
server = app.server
Sample error message and code are given below.
Error message:
[2022-07-06 09:08:36,993] ERROR in app: Exception on /_dash-update-component [POST]
Traceback (most recent call last):
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\dash\dash.py”, line 1297, in dispatch
cb = self.callback_map[output]
KeyError: ‘…EEp_msg.children…EEp_table.data…’

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask\app.py”, line 2447, in wsgi_app
response = self.full_dispatch_request()
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask\app.py”, line 1952, in full_dispatch_request
rv = self.handle_user_exception(e)
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask\app.py”, line 1821, in handle_user_exception
reraise(exc_type, exc_value, tb)
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask_compat.py”, line 39, in reraise
raise value
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask\app.py”, line 1950, in full_dispatch_request
rv = self.dispatch_request()
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\flask\app.py”, line 1936, in dispatch_request
return self.view_functionsrule.endpoint
File “C:\Users\tghosh.STUDENT\Anaconda3\lib\site-packages\dash\dash.py”, line 1335, in dispatch
raise KeyError(msg.format(output)) from missing_callback_function
KeyError: “Callback function not found for output ‘…EEp_msg.children…EEp_table.data…’, perhaps you forgot to prepend the ‘@’?”
10.112.43.194 - - [06/Jul/2022 09:08:36] “POST /_dash-update-component HTTP/1.1” 500 –
Callback function:

@app.callback(Output('EEp_msg', 'children'),
              Output('EEp_table', 'data'),
              Output('FI_plot','children'),
              Input('Bt_add_eep','n_clicks'),
              State('ddEEdesp','value'),
              State('eep_st_time','value'),
              State('eep_end_time','value'),
              prevent_initial_call=True)
def add_eating_episode(n_clicks,desp,sttime,endtime):
    global tfiv
    if n_clicks>0:
#        print('inside n_click')
        arr_hhmmss = sttime.split(':')
        sttime2 = selecteddate+3600*int(arr_hhmmss[0])+60*int(arr_hhmmss[1])
        arr_hhmmss = endtime.split(':')
        endtime2 = selecteddate+3600*int(arr_hhmmss[0])+60*int(arr_hhmmss[1])
        msg = procDB.insert_eating_episode(current_pDBInfo,selecteddate,sttime2,endtime2,
                                      'Image-annotation',2,desp,true_eating_episode=1)
        data = get_updated_EEpdata()
        update_tfiv()
    return msg,data,dcc.Graph(figure = createFIplot(),)

Layout:

def getlayout():
    update_tfiv()
    leftcol = html.Div([
        html.Div(id='FI_plot',
            children=dcc.Graph(
                figure = createFIplot(),
            )    
            ),
        ],style={'padding': 1, 'flex': '70%'})
    

    rightcol = html.Div(children=[
        dcc.ConfirmDialog(
        id='confirm-delete',
        message='Are you sure to delete this?',
        ),
        html.P('Enter Eating Episodes'),
        enterEEp,
        html.Br(),
        html.Button('Add',id='Bt_add_eep', n_clicks=0),#,style = {'width':'150px','height': '40px',}),
        html.Br(),
        html.Div(id='EEp_msg'),
        html.H6('List of Entered Eating Episodes'),
        dash_table.DataTable(
            id='EEp_table',
            columns=[{
                'name': EEptable_col_desp[i-1],
                'id': 'column-{}'.format(i),
                'deletable': False,
                'renamable': False
            } for i in range(1, 4)],
            data=get_updated_EEpdata(),
            editable=True,
            row_deletable=True,
            style_cell = {
                    'font-family': 'cursive',
                    'font-size': '16px',
                    'text-align': 'center'
                },
        ),
        ],style={'padding': 1, 'flex': '30%'})

    layout = html.Div([
        leftcol,
        rightcol,
        ], style={'display': 'flex', 'flex-direction': 'row'})
    
    return layout