Excel repair strips all formulas from large .xlsm after March 2026 security update (KB5002849)

Office 365 (ver 16.111.3) running on Mac Book Pro 16 inch

I have a large accounts .xlsm spread sheet for all my business. I started writing it in 2009 It's full of VBA from printing off invoices and completing VAT returns.  It has worked for many years now albeit slight problems over the years especially after the office 2011 upgrade

 I'm now semi-retired and the last time I used it was in March this year to fill in my VAT form.  Yesterday I started the accounts programme to see the a message box "Alert we found a problem problem the some content..... we can try to recover it Yes/No". clicking yes takes you too another message box "Excel was able to open the file by repairing or removing the unreadable content." view or delete.  View shows you a .xlm file "Removed Part: /xl/vbaProject.bin part.  (Visual Basic for Applications"

The spread sheets are shown but all the VBA has been stripped out as per Florian Boschek

I have tried renaming the file to no avail, trying previous versions of the code the same happens.  However running on a PC (not all the macros run) the macros are still present.

Running the application on Version 14.7.7 Mac 2011 and all works ok

Thank You

Dudley 

Update.  With the help of my old MBP and a Windows 11 Pc I eventually got it to work.

The Excel code had removed all the VB files(Version 4)so I imported them from my old MBP whilst doing this very slowly one file would not load and it was the main menu.  This form loaded ok on both the old MBP and the PC so on the PC I made a very small edit to the wording and exported that file and then imported that form into what was now Version 5 it all worked fine.  I know it's not conclusive but it worked for me.  no doubt there will be more pain tomorrow 

Thanks for your time