Row number in Expression builder

[gpgisandsky]

It could be userful show row number into Expression Builder GUI in order to identify fastly the row when an code error occour.

[JohannesLindner]

Assuming you mean the Espression window in things like Calculate Field:

Right-Click -> Show Line Numbers

Before:

After:

[SimonSchütte_ct]

This feature may not be available in older versions. In case this does not work for someone, update your version. (When I remember correctly, this feature was added in one of the more recent 2.x releases.)

Feature request: Displaying the row numbers should be the default and "Hide row numbers" an option. Also the numbers should not be right aligned as it is too close to the code, better centered.

[gpgisandsky]

I'm sorry I didn't know it. In ArcGIS Pro 2.9 "Show line numbers" option is available on right click menu.