Wrong error message when connecting variable with different units

[rparello]

Describe the bug
If a variable is defined with different incompatible units in different modules, this following error message comes up. The problem is that the error message says it's the 'val' metadata that differ when its in fact the units. Can also append if the units is defined only in one module (but not always for some unclear reason). Makes it complex to debug

Expected behavior
the error message should be : The following inputs, ['Geometry.Geometrie_discipline.nose_landing_gear_length', 'QDV.QDV_discipline.nose_landing_gear_length', 'Structure.Structure_discipline.nose_landing_gear_length'], promoted to 'data:geometry:nose_landing_gear:length', are connected but their metadata entries ['units'] differ

Error message
Collected errors for problem 'Analysis_test':
: The following inputs, ['Geometry.Geometrie_discipline.nose_landing_gear_length', 'QDV.QDV_discipline.nose_landing_gear_length', 'Structure.Structure_discipline.nose_landing_gear_length'], promoted to 'data:geometry:nose_landing_gear:length', are connected but their metadata entries ['val'] differ.
Call .set_input_defaults('data:geometry:nose_landing_gear:length', val=?), where is the model to remove the ambiguity.
: Output units of 'kg' for '_auto_ivc.v86' are incompatible with input units of 'm' for 'Geometry.Geometrie_discipline.nose_landing_gear_length'.
: Output units of 'kg' for '_auto_ivc.v86' are incompatible with input units of 'm' for 'Structure.Structure_discipline.nose_landing_gear_length'.

Environment

• Operating System: Windows 10
• Python environment: Python 3.10.11
• Packages:
  aenum 3.1.15 Advanced Enumerations (compatible with Python's stdlib Enum), NamedTuples, and NamedConstants
  aiofiles 22.1.0 File support for asyncio.
  aiosqlite 0.20.0 asyncio bridge to the standard sqlite3 module
  anyio 4.6.0 High level compatibility layer for multiple asynchronous event loop implementations
  argon2-cffi 23.1.0 Argon2 for Python
  argon2-cffi-bindings 21.2.0 Low-level CFFI bindings for Argon2
  arrow 1.3.0 Better dates & times for Python
  asttokens 2.4.1 Annotate AST trees with source code positions
  attrs 24.2.0 Classes Without Boilerplate
  babel 2.16.0 Internationalization utilities
  beautifulsoup4 4.12.3 Screen-scraping library
  bleach 6.1.0 An easy safelist-based HTML-sanitizing tool.
  build 1.2.2 A simple, correct Python build frontend
  certifi 2024.8.30 Python package for providing Mozilla's CA Bundle.
  cffi 1.17.1 Foreign Function Interface for Python calling C code.
  cfgv 3.4.0 Validate configuration and produce human readable error messages.
  charset-normalizer 3.3.2 The Real First Universal Charset Detector. Open, modern and actively maintained alternative to Chardet.
  chart-studio 1.1.0 Utilities for interfacing with plotly's Chart Studio
  click 8.1.7 Composable command line interface toolkit
  cma 4.0.0 CMA-ES, Covariance Matrix Adaptation Evolution Strategy for non-linear numerical optimization in Python
  colorama 0.4.6 Cross-platform colored terminal text.
  comm 0.2.2 Jupyter Python Comm implementation, for usage in ipykernel, xeus-python etc.
  contourpy 1.3.0 Python library for calculating contours of 2D quadrilateral grids
  coolprop 6.6.0 Open-source thermodynamic and transport properties database
  coverage 7.6.1 Code coverage measurement for Python
  cycler 0.12.1 Composable style cycles
  debugpy 1.8.6 An implementation of the Debug Adapter Protocol for Python
  decorator 5.1.1 Decorators for Humans
  defusedxml 0.7.1 XML bomb protection for Python stdlib modules
  deprecated 1.2.14 Python @deprecated decorator to deprecate old python classes, functions or methods.
  dill 0.3.9 serialize all of Python
  distlib 0.3.8 Distribution utilities
  ensure 1.0.4 Literate BDD assertions in Python with no magic
  et-xmlfile 1.1.0 An implementation of lxml.xmlfile for the standard library
  exceptiongroup 1.2.2 Backport of PEP 654 (exception groups)
  executing 2.1.0 Get the currently executing AST node of a frame, and other information
  fast-oad 1.7.4 FAST-OAD is a framework for performing rapid Overall Aircraft Design
  fast-oad-core 1.7.4 FAST-OAD is a framework for performing rapid Overall Aircraft Design
  fast-oad-cs25 0.7.1 FAST-OAD_CS25 is a FAST-OAD plugin with CS25/FAR25-related models.
  fastjsonschema 2.20.0 Fastest Python implementation of JSON schema
  filelock 3.16.1 A platform independent file lock.
  fonttools 4.54.1 Tools to manipulate font files
  fqdn 1.5.1 Validates fully-qualified domain names against RFC 1123, so that they are acceptable to modern bowsers
  identify 2.6.1 File identification library for Python
  idna 3.10 Internationalized Domain Names in Applications (IDNA)
  iniconfig 2.0.0 brain-dead simple config-ini parsing
  ipopo 1.0.2 A service-oriented component model framework
  ipykernel 6.29.5 IPython Kernel for Jupyter
  ipysheet 0.7.0 Spreadsheet in the Jupyter notebook.
  ipython 8.18.1 IPython: Productive Interactive Computing
  ipython-genutils 0.2.0 Vestigial utilities from IPython
  ipywidgets 7.8.4 IPython HTML widgets for Jupyter
  isoduration 20.11.0 Operations with ISO 8601 durations
  jedi 0.19.1 An autocompletion tool for Python that can be used for text editors.
  jenn 1.0.8 Jacobian-Enhanced Neural Nets (JENN)
  jinja2 3.1.4 A very fast and expressive template engine.
  joblib 1.4.2 Lightweight pipelining with Python functions
  json5 0.9.25 A Python implementation of the JSON5 data format.
  jsonpointer 3.0.0 Identify specific nodes in a JSON document (RFC 6901)
  jsonrpclib-pelix 0.4.3.3 This project is an implementation of the JSON-RPC v2.0 specification (backwards-compatible) as a client library, for Python 2.7 and Python 3. This version is a fork of ...
  jsonschema 4.23.0 An implementation of JSON Schema validation for Python
  jsonschema-specifications 2023.12.1 The JSON Schema meta-schemas and vocabularies, exposed as a Registry
  jupyter-client 8.6.3 Jupyter protocol implementation and client libraries
  jupyter-core 5.7.2 Jupyter core package. A base package on which Jupyter projects rely.
  jupyter-events 0.10.0 Jupyter Event System library
  jupyter-server 2.14.2 The backend—i.e. core services, APIs, and REST endpoints—to Jupyter web applications.
  jupyter-server-fileid 0.9.3 Jupyter Server extension providing an implementation of the File ID service.
  jupyter-server-terminals 0.5.3 A Jupyter Server Extension Providing Terminals.
  jupyter-server-ydoc 0.8.0 A Jupyter Server Extension Providing Y Documents.
  jupyter-ydoc 0.2.5 Document structures for collaborative editing using Ypy
  jupyterlab 3.6.8 JupyterLab computational environment
  jupyterlab-pygments 0.3.0 Pygments theme using JupyterLab CSS variables
  jupyterlab-server 2.27.3 A set of server components for JupyterLab and JupyterLab like applications.
  jupyterlab-widgets 1.1.10 A JupyterLab extension.
  kiwisolver 1.4.7 A fast implementation of the Cassowary constraint solver
  llvmlite 0.43.0 lightweight wrapper around basic LLVM functionality
  lxml 5.3.0 Powerful and Pythonic XML processing library combining libxml2/libxslt with the ElementTree API.
  markupsafe 2.1.5 Safely add untrusted strings to HTML/XML markup.
  matplotlib 3.9.2 Python plotting package
  matplotlib-inline 0.1.7 Inline Matplotlib backend for Jupyter
  mistune 3.0.2 A sane and fast Markdown parser with useful plugins and renderers
  multiprocess 0.70.16 better multiprocessing and multithreading in Python
  nbclassic 1.1.0 Jupyter Notebook as a Jupyter Server extension.
  nbclient 0.10.0 A client library for executing notebooks. Formerly nbconvert's ExecutePreprocessor.
  nbconvert 7.16.4 Converting Jupyter Notebooks (.ipynb files) to other formats. Output formats include asciidoc, html, latex, markdown, pdf, py, rst, script. nbconvert can be used both...
  nbformat 5.10.4 The Jupyter Notebook format
  nbval 0.11.0 A py.test plugin to validate Jupyter notebooks
  nest-asyncio 1.6.0 Patch asyncio to allow nested event loops
  networkx 3.2.1 Python package for creating and manipulating graphs and networks
  nodeenv 1.9.1 Node.js virtual environment builder
  notebook 6.5.4 A web-based notebook environment for interactive computing
  notebook-shim 0.2.4 A shim layer for notebook traits and config
  numba 0.60.0 compiling Python code using LLVM
  numpy 1.26.4 Fundamental package for array computing in Python
  openmdao 3.31.1 OpenMDAO framework infrastructure
  openmdao-extensions 1.3.1 Additional solvers and drivers for OpenMDAO framework
  openpyxl 3.1.5 A Python library to read/write Excel 2010 xlsx/xlsm files
  orjson 3.10.7 Fast, correct Python JSON library supporting dataclasses, datetimes, and numpy
  overrides 7.7.0 A decorator to automatically detect mismatch when overriding a method.
  packaging 24.1 Core utilities for Python packages
  pandas 2.2.3 Powerful data structures for data analysis, time series, and statistics
  pandocfilters 1.5.1 Utilities for writing pandoc filters in python
  parso 0.8.4 A Python Parser
  pathos 0.3.2 parallel graph management and execution in heterogeneous computing
  pillow 10.4.0 Python Imaging Library (Fork)
  pkginfo 1.11.1 Query metadata from sdists / bdists / installed packages.
  platformdirs 4.3.6 A small Python package for determining appropriate platform-specific dirs, e.g. a user data dir.
  plotly 5.24.1 An open-source, interactive data visualization library for Python
  pluggy 1.5.0 plugin and hook calling mechanisms for python
  pox 0.3.5 utilities for filesystem exploration and automated builds
  ppft 1.7.6.9 distributed and parallel Python
  pre-commit 3.8.0 A framework for managing and maintaining multi-language pre-commit hooks.
  prometheus-client 0.21.0 Python client for the Prometheus monitoring system.
  prompt-toolkit 3.0.48 Library for building powerful interactive command lines in Python
  psutil 6.0.0 Cross-platform lib for process and system monitoring in Python.
  pure-eval 0.2.3 Safely evaluate AST nodes without side effects
  pycparser 2.22 C parser in Python
  pydoe 0.3.8 Design of experiments for Python
  pydoe2 1.3.0 Design of experiments for Python
  pydoe3 1.0.4 Design of experiments for Python
  pyfarfadet 0.1.0
  pygments 2.18.0 Pygments is a syntax highlighting package written in Python.
  pyparsing 3.1.4 pyparsing module - Classes and methods to define and execute parsing grammars
  pyproject-hooks 1.2.0 Wrappers to call pyproject.toml-based build backend hooks.
  pytest 8.3.3 pytest: simple powerful testing with Python
  pytest-cov 5.0.0 Pytest plugin for measuring coverage.
  python-dateutil 2.9.0.post0 Extensions to the standard Python datetime module
  python-json-logger 2.0.7 A python library adding a json log formatter
  pytz 2024.2 World timezone definitions, modern and historical
  pywin32 306 Python for Window Extensions
  pywinpty 2.0.13 Pseudo terminal support for Windows from Python.
  pyyaml 6.0.2 YAML parser and emitter for Python
  pyzmq 26.2.0 Python bindings for 0MQ
  referencing 0.35.1 JSON Referencing + Python
  requests 2.32.3 Python HTTP for Humans.
  retrying 1.3.4 Retrying
  rfc3339-validator 0.1.4 A pure python RFC3339 validator
  rfc3986-validator 0.1.1 Pure python rfc3986 validator
  rpds-py 0.20.0 Python bindings to Rust's persistent data structures (rpds)
  ruamel-yaml 0.17.40 ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order
  ruamel-yaml-clib 0.2.8 C version of reader, parser and emitter for ruamel.yaml derived from libyaml
  ruff 0.6.4 An extremely fast Python linter and code formatter, written in Rust.
  salib 1.5.1 Tools for global sensitivity analysis. Contains Sobol', Morris, FAST, DGSM, PAWN, HDMR, Moment Independent and fractional factorial methods
  scikit-learn 1.5.2 A set of python modules for machine learning and data mining
  scipy 1.13.1 Fundamental algorithms for scientific computing in Python
  send2trash 1.8.3 Send file to trash natively under Mac OS X, Windows and Linux
  six 1.16.0 Python 2 and 3 compatibility utilities
  smt 2.7.0 The Surrogate Modeling Toolbox (SMT)
  sniffio 1.3.1 Sniff out which async library your code is running under
  soupsieve 2.6 A modern CSS selector implementation for Beautiful Soup.
  stack-data 0.6.3 Extract data from python stack frames and tracebacks for informative displays
  stdatm 0.4.3 Numpy-oriented Standard Atmosphere model
  tabulate 0.9.0 Pretty-print tabular data
  tenacity 9.0.0 Retry code until it succeeds
  terminado 0.18.1 Tornado websocket backend for the Xterm.js Javascript terminal emulator library.
  threadpoolctl 3.5.0 threadpoolctl
  tinycss2 1.3.0 A tiny CSS parser
  tomli 2.0.1 A lil' TOML parser
  tomli-w 1.0.0 A lil' TOML writer
  tomlkit 0.13.2 Style preserving TOML library
  tornado 6.4.1 Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
  tqdm 4.66.5 Fast, Extensible Progress Meter
  traitlets 5.14.3 Traitlets Python configuration system
  types-python-dateutil 2.9.0.20240906 Typing stubs for python-dateutil
  typing-extensions 4.12.2 Backported and Experimental Type Hints for Python 3.8+
  tzdata 2024.2 Provider of IANA time zone data
  uri-template 1.3.0 RFC 6570 URI Template Processor
  urllib3 2.2.3 HTTP library with thread-safe connection pooling, file post, and more.
  virtualenv 20.26.6 Virtual Python Environment builder
  wcwidth 0.2.13 Measures the displayed width of unicode strings in a terminal
  webcolors 24.8.0 A library for working with the color formats defined by HTML and CSS.
  webencodings 0.5.1 Character encoding aliases for legacy web content
  websocket-client 1.8.0 WebSocket client for Python with low level API options
  widgetsnbextension 3.6.9 IPython HTML widgets for Jupyter
  wop 2.5.5 WhatsOpt Command Line Interface
  wrapt 1.16.0 Module for decorators, wrappers and monkey patching.
  xdsmjs 2.0.0 XDSMjs Python module
  y-py 0.6.2 Python bindings for the Y-CRDT built from yrs (Rust)
  yabox 1.1.0 Yet another black-box optimization library for Python
  ypy-websocket 0.8.4 WebSocket connector for Ypy

[christophe-david]

Actually, this error message comes from OpenMDAO. And in the present case, the important part of the message is the last part, where the incompatibility of units is exposed.