Strapi run develop gives frequent server error, plus: getting "an error occured" message when trying to save changes in admin panel and strapi goes into endless load mode

@Eventyret and @DMehaffy , thank you both for trying to help me - I am really very grateful!

I have
npm 6.14.15
node v14.17.6
using npm (not yarn)

I did try to open another strapi project, and this opens fine when I just ignore the pointless :wink: messages from audit and run develop (I still get the same vulnerability messages there about the tar files etc),

So, it is probably as you say @DMehaffy - that I did something stupid like trying to run audit fix in some kind of desperation to fix my problems and ignoring the breaking changes message… probably. (:see_no_evil:)

Okay, so I do not know if this helps in any way, but the package.json file on the strapi that works is:

{
  "name": "api",
  "private": true,
  "version": "0.1.0",
  "description": "Noroff Semester project 2",
  "scripts": {
    "develop": "strapi develop",
    "start": "strapi start",
    "build": "strapi build",
    "strapi": "strapi"
  },
  "devDependencies": {},
  "dependencies": {
    "knex": "<0.20.0",
    "sqlite3": "latest",
    "strapi": "^3.6.8",
    "strapi-admin": "^3.6.8",
    "strapi-connector-bookshelf": "^3.6.8",
    "strapi-plugin-content-manager": "^3.6.8",
    "strapi-plugin-content-type-builder": "^3.6.8",
    "strapi-plugin-email": "^3.6.8",
    "strapi-plugin-upload": "^3.6.8",
    "strapi-plugin-users-permissions": "^3.6.8",
    "strapi-utils": "^3.6.8"
  },
  "author": {
    "name": "A Strapi developer"
  },
  "strapi": {
    "uuid": "8715cbed-a6ed-4700-bc41-444293351d4e"
  },
  "engines": {
    "node": ">=10.0.0",
    "npm": ">=6.0.0"
  },
  "license": "MIT"
}

-While the package.json on the stapi that will not run is:

{
  "name": "osebro-antikvariat",
  "private": true,
  "version": "0.1.0",
  "description": "A Strapi application",
  "scripts": {
    "develop": "strapi develop",
    "start": "strapi start",
    "build": "strapi build",
    "strapi": "strapi"
  },
  "dependencies": {
    "chokidar": "^3.5.2",
    "css-loader": "^6.2.0",
    "glob-parent": "^6.0.1",
    "jquery": "^3.6.0",
    "knex": "0.21.18",
    "mysql": "2.18.1",
    "strapi": "^3.6.8",
    "strapi-admin": "3.6.8",
    "strapi-connector-bookshelf": "3.6.8",
    "strapi-plugin-content-manager": "3.6.8",
    "strapi-plugin-content-type-builder": "3.6.8",
    "strapi-plugin-email": "3.6.8",
    "strapi-plugin-i18n": "3.6.8",
    "strapi-plugin-upload": "3.6.8",
    "strapi-plugin-users-permissions": "3.6.8",
    "strapi-utils": "3.6.8",
    "tar": "^6.1.11",
    "url-loader": "^4.1.1",
    "webpack": "^4.46.0"
  },
  "author": {
    "name": "A Strapi developer"
  },
  "strapi": {
    "uuid": "e441a5ea-6f26-47bd-b368-139f1cb3da35"
  },
  "engines": {
    "node": ">=10.16.0 <=14.x.x",
    "npm": ">=6.0.0"
  },
  "license": "MIT"
}

-And even I can see that I have a lot of stuff going on in the strapi project that doesn’t work…
(I have python installed - Python3.9)