• Added a warning when an app doesn't specify a Python version and instead relies upon the default/cached version. (#1787)
• Improved the instructions for migrating from runtime.txt to .python-version. (#1783)
• Improved the error messages shown when .python-version, runtime.txt or Pipfile.lock contain an invalid Python version. (#1783 and #1786)
• Improved the rendering of the error message shown when .python-version or runtime.txt contain stray invisible characters (such as ASCII control codes). (#1783)
• Improved the upgrade instructions shown for EOL and unsupported Python versions. (#1783 and #1786)
• Improved the error messages shown when no Python package manager files are found. (#1787)