Hi SSE@TUE,
Based on my research, it is possible to upgrade directly from 2403 to 2503.
However, it might be safer and more stable to first upgrade to 2409 and then proceed to 2503. This approach allows you to address any issues incrementally and ensures that your environment is fully prepared for the latest version.
For additional information review:
- Checklist for installing update 2503 for Configuration Manager
- Summary of changes in Configuration Manager current branch, version 2503
If you find the answer above helpful, please Accept the answer to help anyone in the community who might have a similar question to quickly find the solution.