Project crash every time i open it because of a new blueprint code

Hi everyone !
I have an issue with a huge project i’m working on … I had no problem in 4 months but now, when i open it : it just crash … First of all, i thought it was because of corrupted blueprints classes. So i tried to find out which class was causing this crash : I found that 2 objects were causing the crash. So i deleted them. The first one was not important but the second one was the class for the objects we drop in the game. So now the project was able to be opened, i recreate the blueprint (with a different name) and made all the changes i need to make it work again. After that, i have decided to save all and try to restart unreal to see if the problem persists. And when i tried to open it, it crashed again. So it seems that a portion of code in this blueprint is causing crash. I don"t know why because i made this class like 3 months ago and when i recode it, it still crash…
I’m working on unreal engine 4.19 and the last thing i’ve done the day before the crash happened was working on saves of the building we can make in game. I linked the crash file, i don"t know if it’s the good one.link text

Hello,

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Thanks