Completly stuck, code works locally but not on the server [closed]

Last weeks i’ve been working on a website that works perfectly locally however upon uploading the files to the server i get alot of errors in the console and things like adding items in the database to autosuggesting in the search bar that no longer work. I can’t seem to identify (probably because to my knowledge it should work).

All i can think of doing ahead of time without sharing 50 files of php/javascript is just stating the errors i see in the console first, and if anyone could help that’d be much appreciated (I know it’s a bit of a hassle to help me with it like this but I have no clue what to do anymore)

Even just suggestions on how to go about finding the problem would probably help me alot.

On index.php

index.php:82 Uncaught TypeError: Cannot read properties of null (reading 'addEventListener')
    at index.php:82:10

This error is found on every page :

util.js:68 Uncaught TypeError: Cannot read properties of undefined (reading 'fn')
    at util.js:68:7
    at util.js:10:15
    at bootstrap.min.js:6:200
    at bootstrap.min.js:6:236

The auto suggesting search feature :

jquery-3.6.4.min.js:2          POST http://removedforprivacyreasons(itiscorrect)/rsflips/rsflips1/includes/searchItems.php 500 (Internal Server Error)
send @ jquery-3.6.4.min.js:2
ajax @ jquery-3.6.4.min.js:2
(anonymous) @ handlerSearchInput.js:8
dispatch @ jquery-3.6.4.min.js:2
y.handle @ jquery-3.6.4.min.js:2
handlerSearchInput.js:72 Error: Internal Server Error

So far that seem to be the only errors so less than i remember there being from yesterday but i’m still lost. Thanks in advance everyone!