diff --git a/src/delta_barth/analysis/forecast.py b/src/delta_barth/analysis/forecast.py
index 15fb198..155d352 100644
--- a/src/delta_barth/analysis/forecast.py
+++ b/src/delta_barth/analysis/forecast.py
@@ -10,7 +10,7 @@ from xgboost import XGBRegressor
 
 from delta_barth.analysis import parse
 from delta_barth.constants import COL_MAP_SALES_PROGNOSIS, FEATURES_SALES_PROGNOSIS
-from delta_barth.types import CustomerDataSalesForecast, FcErrorCodes
+from delta_barth.types import CustomerDataSalesForecast, DataPipelineErrors
 
 if TYPE_CHECKING:
     from delta_barth.api.common import SalesPrognosisResponse
@@ -105,7 +105,7 @@ def sales_per_customer(
 
     # check data availability
     if len(df_cust) < min_num_data_points:
-        return FcErrorCodes.DATA_TOO_FEW_POINTS, None
+        return DataPipelineErrors.DATA_TOO_FEW_POINTS, None
     else:
         # Entwicklung der Umsätze: definierte Zeiträume Monat
         df_cust["year"] = df_cust["date"].dt.year
@@ -144,4 +144,4 @@ def sales_per_customer(
         test = test.reset_index(drop=True)
 
         # umsetzung, prognose
-        return FcErrorCodes.SUCCESS, test
+        return DataPipelineErrors.SUCCESS, test
diff --git a/src/delta_barth/api/common.py b/src/delta_barth/api/common.py
index a1076ad..dbb5b06 100644
--- a/src/delta_barth/api/common.py
+++ b/src/delta_barth/api/common.py
@@ -5,10 +5,10 @@ from datetime import datetime as Datetime
 from typing import Final, Never
 
 import requests
-from pydantic import BaseModel, PositiveInt
+from pydantic import BaseModel, PositiveInt, SkipValidation
 from requests import Response
 
-from delta_barth.constants import HTTP_CURRENT_CONNECTION, KnownApiErrorCodes
+from delta_barth.constants import HTTP_CURRENT_CONNECTION, KnownDelBarApiErrorCodes
 from delta_barth.errors import (
     ApiConnectionError,
     UnknownApiErrorCode,
@@ -113,7 +113,7 @@ def login(
     if resp.status_code == 200:
         response = LoginResponse(**resp.json())
         HTTP_CURRENT_CONNECTION.add_session_token(response.token)
-    elif resp.status_code in KnownApiErrorCodes.COMMON.value:
+    elif resp.status_code in KnownDelBarApiErrorCodes.COMMON.value:
         err = DelBarApiError(status_code=resp.status_code, **resp.json())
         response = LoginResponse(token="", error=err)
     else:  # pragma: no cover
@@ -142,7 +142,7 @@ def logout(
     if resp.status_code == 200:
         response = LogoutResponse()
         HTTP_CURRENT_CONNECTION.remove_session_token()
-    elif resp.status_code in KnownApiErrorCodes.COMMON.value:
+    elif resp.status_code in KnownDelBarApiErrorCodes.COMMON.value:
         err = DelBarApiError(status_code=resp.status_code, **resp.json())
         response = LogoutResponse(error=err)
     else:  # pragma: no cover
@@ -153,8 +153,8 @@ def logout(
 
 # ** sales data
 class SalesPrognosisRequestP(BaseModel):
-    FirmaId: int | None
-    BuchungsDatum: Datetime | None
+    FirmaId: SkipValidation[int | None]
+    BuchungsDatum: SkipValidation[Datetime | None]
 
 
 class SalesPrognosisResponseEntry(BaseModel):
@@ -192,7 +192,7 @@ def get_sales_prognosis_data(
     response: SalesPrognosisResponse
     if resp.status_code == 200:
         response = SalesPrognosisResponse(**resp.json())
-    elif resp.status_code in KnownApiErrorCodes.COMMON.value:  # pragma: no cover
+    elif resp.status_code in KnownDelBarApiErrorCodes.COMMON.value:  # pragma: no cover
         err = DelBarApiError(status_code=resp.status_code, **resp.json())
         response = SalesPrognosisResponse(daten=tuple(), error=err)
     else:  # pragma: no cover
diff --git a/src/delta_barth/constants.py b/src/delta_barth/constants.py
index 43b25cc..408bcce 100644
--- a/src/delta_barth/constants.py
+++ b/src/delta_barth/constants.py
@@ -3,7 +3,9 @@ from typing import Final
 
 from delta_barth.types import CurrentConnection, HttpContentHeaders
 
-# ** API connection management
+# ** error handling
+DEFAULT_INTERNAL_ERR_CODE: Final[int] = 100
+
 HTTP_BASE_CONTENT_HEADERS: Final[HttpContentHeaders] = {
     "Content-type": "application/json",
     "Accept": "application/json",
@@ -14,7 +16,7 @@ HTTP_CURRENT_CONNECTION: Final[CurrentConnection] = CurrentConnection(
 )
 
 
-class KnownApiErrorCodes(enum.Enum):
+class KnownDelBarApiErrorCodes(enum.Enum):
     COMMON = frozenset((400, 401, 409, 500))
 
 
diff --git a/src/delta_barth/errors.py b/src/delta_barth/errors.py
index 430a192..0a1e5b5 100644
--- a/src/delta_barth/errors.py
+++ b/src/delta_barth/errors.py
@@ -1,3 +1,14 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Final
+
+from delta_barth.constants import DEFAULT_INTERNAL_ERR_CODE
+from delta_barth.types import DataPipelineErrors, doptResponseError
+
+if TYPE_CHECKING:
+    from delta_barth.types import ErrorDescription
+
+
 class UnspecifiedRequestType(Exception):
     """exception raised if for a given API endpoint a not defined operation is requested"""
 
@@ -12,3 +23,45 @@ class ApiConnectionError(Exception):
 
 class FeaturesMissingError(Exception):
     """exception raised if needed features are missing"""
+
+
+## ** internal error handling
+DATA_PIPELINE_ERRORS_DESCR: Final[tuple[ErrorDescription, ...]] = (
+    ("SUCCESS", 0, "Erfolg"),
+    ("TOO_FEW_POINTS", 1, "Datensatz besitzt nicht genügend Datenpunkte"),
+    ("BAD_QUALITY", 2, "Prognosequalität des Modells unzureichend"),
+)
+
+
+class ErrorManager:
+    def __init__(self) -> None:
+        self._data_pipelines: DataPipelineErrors | None = None
+        self._parse_data_pipeline_errors()
+
+    @property
+    def data_pipelines(self) -> DataPipelineErrors:
+        assert self._data_pipelines is not None, (
+            "tried to access not parsed data pipeline errors"
+        )
+        return self._data_pipelines
+
+    def _parse_data_pipeline_errors(self) -> None:
+        if self._data_pipelines is not None:
+            return
+        parsed_errors: dict[str, doptResponseError] = {}
+        for err in DATA_PIPELINE_ERRORS_DESCR:
+            parsed_errors[err[0]] = doptResponseError(status_code=err[1], description=err[2])
+
+        self._data_pipelines = DataPipelineErrors(**parsed_errors)
+
+    def internal_error(
+        self,
+        description: str,
+        message: str = "",
+        err_code: int = DEFAULT_INTERNAL_ERR_CODE,
+    ) -> doptResponseError:
+        return doptResponseError(
+            status_code=err_code,
+            description=description,
+            message=message,
+        )
diff --git a/src/delta_barth/types.py b/src/delta_barth/types.py
index 334a774..719328a 100644
--- a/src/delta_barth/types.py
+++ b/src/delta_barth/types.py
@@ -4,9 +4,25 @@ from dataclasses import dataclass, field
 from typing import NotRequired, TypeAlias, TypedDict
 
 import pandas as pd
-
+from pydantic import BaseModel, SkipValidation
 
 # ** API
+ErrorDescription: TypeAlias = tuple[str, int, str]
+
+
+class doptResponseError(BaseModel):
+    status_code: SkipValidation[int]
+    description: SkipValidation[str]
+    message: SkipValidation[str] = ""
+
+
+@dataclass(slots=True)
+class DataPipelineErrors:
+    SUCCESS: doptResponseError
+    TOO_FEW_POINTS: doptResponseError
+    BAD_QUALITY: doptResponseError
+
+
 class HttpRequestTypes(enum.StrEnum):
     GET = enum.auto()
     POST = enum.auto()
@@ -73,10 +89,4 @@ class CustomerDataSalesForecast:
     sales: list[float] = field(default_factory=list)
 
 
-class FcErrorCodes(enum.IntEnum):
-    SUCCESS = 0
-    DATA_TOO_FEW_POINTS = 1
-    DATA_BAD_QUALITY = 2
-
-
-FcResult: TypeAlias = tuple[FcErrorCodes, pd.DataFrame | None]
+FcResult: TypeAlias = tuple[DataPipelineErrors, pd.DataFrame | None]
diff --git a/tests/api/test_common.py b/tests/api/test_common.py
index db3b4ab..9bffcde 100644
--- a/tests/api/test_common.py
+++ b/tests/api/test_common.py
@@ -105,8 +105,7 @@ def test_login_logout(credentials, api_base_url):
     assert resp.error.message == "Nutzer oder Passwort falsch."
 
 
-# @pytest.mark.api_con_required
-@pytest.mark.new
+@pytest.mark.api_con_required
 def test_get_sales_prognosis_data(credentials, api_base_url):
     resp = common.login(
         base_url=api_base_url,
diff --git a/tests/test_errors.py b/tests/test_errors.py
new file mode 100644
index 0000000..d27ebf5
--- /dev/null
+++ b/tests/test_errors.py
@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+from dataclasses import asdict
+from typing import Any, cast
+
+import pytest
+
+from delta_barth import errors
+from delta_barth.types import doptResponseError
+
+
+def test_error_manager_parsing():
+    predef_errs = errors.DATA_PIPELINE_ERRORS_DESCR
+
+    err_mgr = errors.ErrorManager()
+    assert err_mgr.data_pipelines is not None
+    parsed_pipe_errs = err_mgr.data_pipelines
+    parsed_pipe_errs = asdict(parsed_pipe_errs)
+
+    for err in predef_errs:
+        dopt_err = cast(doptResponseError, parsed_pipe_errs[err[0]])
+        assert isinstance(dopt_err, doptResponseError)
+        assert dopt_err.status_code == err[1]
+        assert dopt_err.description == err[2]
+        assert dopt_err.message == ""
+
+    err_mgr._parse_data_pipeline_errors()
+
+
+def test_error_manager_internal():
+    DESCRIPTION = "test case"
+    MESSAGE = "an error occurred"
+    ERR_CODE = 101
+
+    err_mgr = errors.ErrorManager()
+    new_err = err_mgr.internal_error(
+        description=DESCRIPTION,
+        message=MESSAGE,
+        err_code=ERR_CODE,
+    )
+    assert new_err.status_code == ERR_CODE
+    assert new_err.description == DESCRIPTION
+    assert new_err.message == MESSAGE