Find and replace ".alt" to ".ss01"

Hello friends

I have a question.
I have all my alternates characters with the old “.alt”, could you please help me whit the script for change to “.ss01”?
I tried, but the program crashed.
Maybe I am making something wrong.

I copied a script that made the same but from “.sc” to “.smpc” and it doesn’t work. :’(

Thanks in advance

Select all glyphs and press cmd+shift+F.

and then?

Put ‘.alt’ in Search and ‘.ss01’ in Replace. and uncheck the Regex option. This works just like search and replace in any text based app.

What version do you have? Did you send crash reports (the one that comes up when you restart the app).

THANK YOU GEORG, you rescued me an entire week of work.
Thank you very much.
I have the last version, I think the crash is because I made something wrong.