The SAP Upgrade Trap: Why Some Systems Perform Worse After an Upgrade

We’ve all heard it before:

“Let’s upgrade. It’ll fix the bugs, improve performance, and unlock innovation.”

And in theory, that’s true. But in reality? Many SAP systems perform worse after an upgrade.

• Reports get slower
• Interfaces break silently
• Custom code behaves unpredictably
• End users get frustrated
• Critical processes come to a halt

So what’s really going wrong?

The myth: An SAP upgrade = instant performance and functionality gains The reality: An SAP upgrade exposes everything you didn’t clean up before

Let’s talk about why this happens—and how to avoid falling into the SAP upgrade trap.

Why Systems Underperform After an Upgrade

1. Simplification Items Are Ignored or Misunderstood

SAP provides a Simplification Item List (SIL) with every S/4HANA version. It’s meant to tell you what’s changed, deprecated, or redesigned.

But most teams:

• Skim the list
• Focus only on mandatory fixes
• Miss impact in downstream or niche processes

Result: Core logic changes silently break things like pricing conditions, ATP checks, or master data behavior.

Fix: Treat the Simplification List as a project within your project. Own it. Analyze it. Test for it.

2. Custom Code Is “Lifted and Shifted” Without Re-Validation

Most projects bring forward old custom code without refactoring or re-testing it.

What’s wrong with that?

• It was built for ECC logic, not HANA-optimized tables
• It may call deprecated function modules
• It often conflicts with new Fiori apps or CDS views

Result: Z-reports crash. BAPIs behave inconsistently. Authorizations fail.

Fix: Run Custom Code Migration (CCM) early. Use ATC (ABAP Test Cockpit) to assess and clean Z-code. Only migrate what’s still relevant.

3. Regression Testing Is Weak or Nonexistent

Most upgrade projects focus on “will it run” testing. But they ignore “will it run the same way as before”.

And that’s where the pain begins.

• Vendor payments fail due to format changes
• Purchase requisitions trigger wrong release strategies
• Batch jobs run slower or crash at runtime

Fix: Define end-to-end regression test scenarios early. Include:

• Interfaces
• Background jobs
• Master data maintenance
• Key reports and forms

4. Performance Bottlenecks Are Introduced with New Logic

New versions of SAP often rewire core processes (e.g., MRP, ATP, FICO logic). If your custom code or business volume wasn’t designed for it, you’ll feel the pain.

Example:

• Old logic used buffer tables. New logic calls real-time CDS views—slower if not indexed.
• Batch programs suddenly take hours instead of minutes.

Fix: Involve Basis and Technical team to simulate loads. Test with production-like data. Monitor SM66, ST03N, and ST05 for bottlenecks.

How to Make Sure Your Upgrade Actually Improves Things

• Assign owners to each simplification item not just functional leads
• Retire or refactor custom code don’t blindly migrate
• Include interface testing and cutover mock runs
• Don’t just “test what’s new” test what you need to protect
• Re-evaluate authorizations and Fiori tiles (many changes are tile-specific)

Final Thought

An SAP upgrade is like a renovation: You’re not just layering on a new coat of paint you’re exposing old plumbing and hidden wiring.

If you skip the inspection, don’t be surprised when the lights flicker or the pipes burst.

Upgrades are an opportunity but only if you respect what they expose.

Have you experienced performance drops or process breaks after an SAP upgrade? What helped you fix it?

Let’s share and prevent others from falling into the trap.

#SAP #SAPS4HANA #SAPUpgrade #SimplificationList #CustomCode #SAPTesting #SAPConsulting #DigitalCore #RegressionTesting #CleanCore #SAPPerformance #ERPProjects