I have the next requirement: When users set lead to 'Qualified', I want a way to prevent them to editing any field.
I've tried some things like validation rules like this:
ISPICKVAL(PRIORVALUE(Status),"Qualified")
This works fine unitl a user tries to convert it, the validation rule takes action and does not allow him to finish the conversion (I think is because in background the lead is chaging its status to 'closed').
What is the best way to achieve this?