Pop up/ Msgbox if user create same name in dash plotly

Question

I m trying to create a msgbox in Dash plotly if a user try to enter the same datain a dataframe.

Example :

Name	Another header
test1	row1
test4	row
test1	row

==> Pop up while saving the third line : Attention ! the name already exist in the dataframe, please try another.

I didn't find any information about this topic.. pop up with condition if. Can you help me please ?

Thank you