After applying the DiagBox 7.57 fix, don't assume victory. Run a real-world test.
This version is often the "sweet spot" for hobbyists because it supports a wide range of PSA vehicles (Citroën and Peugeot) from the mid-2000s up to approximately 2014-2015. Beyond version 7.58, many users report increased stability issues with "clone" interfaces. step-by-step guide for a clean install, or are you seeing a specific error code like "Error 202"?
The most reliable fix for diagbox errors is to ensure the column it resides in has a fixed width. You cannot rely on LaTeX to "guess" the width when a diagonal split is involved.