heres how to do an Umbrella run (having umbrella at the very start of the game, because people were having trouble with doing it, I went and made a save file you can use. Its the the value around 100 values down that is “1″, when that value is 1 it means you have the umbrella, when that value is 0, you don’t have it. so if you go down to that value on your current save you can change it to 1 and have the umbrella with you.
First, to find the saves, on Windows the save files are located at C:/Users/<Your User>/AppData/Undertale
on Macs its located at User/<Your User>/Library[Hidden folder]/Application Support/com.tobyfox.undertale/
because Apple believes we are all big babies that will screw up our computers if given free reign, the newest versions of OSX hide the Library folder so you can’t find it, so if you have that problem, see how to fix it here
open up your save “file0” with a plain text editor, like TextEdit. then replace what is in there by copy/pasting the following, replace Umbrella with whatever name you want to have.