Forum Discussion
Excel repair strips all formulas from large .xlsm after March 2026 security update (KB5002849)
Hi everyone, I'm a master's student at Karolinska Institutet in Stockholm. My thesis is a health economic cost-effectiveness model built entirely in Excel — a gender-neutral static Markov cohort ...
Honestly, this doesn’t look like file corruption. It feels more like something changed in Excel after that March 2026 update.
If your formulas are still visible in the XML (<f> tags), then Excel is probably removing them during the repair process on purpose likely because of stricter security rules.
A couple of things you can try:
- Open the file on a different system (preferably Windows if you're on Mac)
- Download it and open it offline instead of OneDrive/Excel Online
- Try an older Excel version if you have access
- If the file is very large/complex, try simplifying it a bit (remove unused stuff, split sheets, etc.)
This update seems to have tightened how Excel handles big or complex .xlsm files, so it might be hitting some internal limit or flagging something as unsafe.
If nothing works, you might have to rebuild parts of it since the formulas are technically still there in the XML.