ServersideOutputTransformation with multiple pages

I want to create a multipage app with the ServersideOutputTransformation so that I can access data generated on one page on another page. For this, I have oriented on this instruction. I also tried this approach from the forum.
The usage of background callbacks as here in the example as well as in the documentation are not possible for me, because the callbacks should only be executed when triggered and not multiple times in the background

My goal is, that I can simply return a variable as an Output from a callback-function and use it somewhere in my application on any page. Just as long as the ID is mentioned as an input to the callback-function

The current code structure is as follows:

import dash
from dash import Dash
import dash_bootstrap_components as dbc
from dash_extensions.enrich import DashProxy, Output, Input, State, Serverside, html, dcc, ServersideOutputTransform, FileSystemBackend

# styling the sidebar


PARAMETERS, APP = core.authFun.initiate(user=None)

app = DashProxy(__name__, use_pages=True, transforms=[ServersideOutputTransform()])

#definition of the sidebar. Use HTML components
sidebar = html.Div([])

app.layout = dbc.Container([
    dcc.Location(id='url', refresh=False),



            ServersideOutput('oID', 'data'),
        Input('url', 'search'),
def getAADToken(queryParameter): #Just run on trigger input
    acquire_tokens_result = {'initial': 'runApp'}
    oID = ''

    if queryParameter != '' and 'code' in queryParameter:
        oID = 'just mocked, the value gets generated by function and is a String'

    return  oID 

if __name__ == '__main__': = 'localhost', port = '8050', debug=True)

The file I want to use the contend of ‘oID’ is as follows:

import dash
from dash_extensions.enrich import DashProxy, Output, Input, State, Serverside, html, dcc, ServersideOutputTransform, FileSystemBackend
import dash_bootstrap_components as dbc

        name = 'ADP',
        path = '/adp')


app = dash.get_app()

workspacesSelect = html.Tr([
    html.H2('Select a workspace:', style={'width': 550}), 
...  I have left out the whole layout of the page because it is not relevant

#### Functions with callback
        Output('workspaceDropdown', 'options'),
            Input('url', 'pathname'),
            Input('oID', 'data')
def getWorkspaces(path, oID):
        if path == '/adp':
            workspaces = get_workspaces(oID) #here I want to use oID which I get from
            workspacesList = list(workspaces.keys())

            return workspacesList
    except IndexError as e:

    return []

The structure of my repository is as follows

When I execute the code, I get the following Exception
Traceback (most recent call last):

  File "C:\Users\....\repo-folder\", line 66, in <module>
    app = DashProxy(__name__, use_pages=True, transforms=[ServersideOutputTransform()])
  File "C:\Users\...\lib\site-packages\dash_extensions\", line 358, in __init__
    super().__init__(*args, prevent_initial_callbacks=prevent_initial_callbacks, **kwargs)
  File "C:\Users\...\lib\site-packages\dash\", line 511, in __init__
  File "C:\Users\...\lib\site-packages\dash\", line 589, in init_app
  File "C:\Users\...\lib\site-packages\dash\", line 2040, in enable_pages
  File "C:\Users\...\lib\site-packages\dash\", line 435, in _import_layouts_from_pages
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "C:\Users\...\repo-folder\pages\", line 135, in <module>
  File "C:\Users\....\lib\site-packages\dash_extensions\", line 364, in callback
    return self.blueprint.callback(*args, **kwargs)
AttributeError: 'DashProxy' object has no attribute 'blueprint'