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I get an error when using the command "npm run start" for my react project

I am new to coding and would appreciate some help with this I get the following error when I try to run my react app: npm run start
Failed to compile.
Loading PostCSS "postcss-normalize" plugin failed: Cannot find module 'postcss-normalize'
Require stack:
/Users/abc/node_modules/postcss-loader/dist/utils.js
/Users/abc/node_modules/postcss-loader/dist/index.js
/Users/abc/node_modules/postcss-loader/dist/cjs.js
/Users/abc/node_modules/loader-runner/lib/loadLoader.js
/Users/abc/node_modules/loader-runner/lib/LoaderRunner.js
/Users/abc/node_modules/webpack/lib/NormalModule.js
/Users/abc/node_modules/webpack-manifest-plugin/dist/index.js
/Users/abc/node_modules/react-scripts/config/webpack.config.js
/Users/abc/node_modules/react-scripts/scripts/start.js
(#/Users/abc/node_modules/bootstrap/dist/css/bootstrap.css)
ERROR in ./node_modules/bootstrap/dist/css/bootstrap.css (./node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[1].oneOf[5].use[1]!./node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[1].oneOf[5].use[2]!./node_modules/source-map-loader/dist/cjs.js!./node_modules/bootstrap/dist/css/bootstrap.css)
./node_modules/bootstrap/dist/css/bootstrap.css (./node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[1].oneOf[5].use[1]!./node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[1].oneOf[5].use[2]!./node_modules/source-map-loader/dist/cjs.js!./node_modules/bootstrap/dist/css/bootstrap.css)
Module Error (from ./node_modules/postcss-loader/dist/cjs.js):
Loading PostCSS "postcss-normalize" plugin failed: Cannot find module 'postcss-normalize'
Require stack:
/Users/abc/node_modules/postcss-loader/dist/utils.js
/Users/abc/node_modules/postcss-loader/dist/index.js
/Users/abc/node_modules/postcss-loader/dist/cjs.js
/Users/abc/node_modules/loader-runner/lib/loadLoader.js
/Users/abc/node_modules/loader-runner/lib/LoaderRunner.js
/Users/abc/node_modules/webpack/lib/NormalModule.js
/Users/abc/node_modules/webpack-manifest-plugin/dist/index.js
/Users/abc/node_modules/react-scripts/config/webpack.config.js
/Users/abc/node_modules/react-scripts/scripts/start.js
(#/Users/abc/node_modules/bootstrap/dist/css/bootstrap.css)
Thank you so much
I've tried updating to the latest version of node and npm, however, that did not help. I've also verified my code several times as I'm mostly practicing along with a course. Thank you.

As it appears this error will temporarily get fixed by installing the latest version of Node.js.
So to fix this follow these steps:
Download and install the latest Node.js version (recommended for most users, which is 16.15.0 at this moment).
Delete your node_modules directory from your project. Then you can optionally clear npm cache with npm cache clean and verify it with npm cache verify.
Delete package-lock.json/yarn.lock file.
Reinstall all of the dependencies and create a new dependency tree using one of the following commands: npm i/npm install/yarn/yarn install.
Note1: If in any case, you use node-sass in React projects yet, it is recommended to use sass instead.
Note2: In some cases skipping step 1 will also work as expected, but I recommend upgrading the Node.js version if you do not have other dependencies to prevent that.
Note3: As #IvaniltonBezerra mentions in the comments, some app builds may throw errors, since upgrading Node.js to its latest version will upgrade the npm as well it may not compatible with your current dependency tree in production, so to prevent such a problem you have to use --legacy-peer-deps to restore the old behaviour of the old dependencies.
Update
This is now seem to be permanently solved in PostCSS Preset Env and following the above steps with skipping step 1 will also solve the problem.

Error: Unable to resolve module `#react-native-community/toolbar-android`

Weirdly, the react-native-vector-icons was working well but by using ^ ("^6.6.0") for its version in the package.json file on the new release this error happens.
It's weird because two days ago it works well but now starting of my project ran to this error:
error: Error: Unable to resolve module #react-native-community/toolbar-android from node_modules\react-native-vector-icons\lib\toolbar-android.js: #react-native-community/toolbar-android could not be found within the project.

After reading this issue and trying many solutions I reach to two solutions:
You can delete all node_modules folder and put the version of react-native-vector-icons to "6.6.0" instead of "^6.6.0" and then install all packages again. absolutely, it is better to delete all caches and builds and start everything again. (NOT Recommended)
You can install the #react-native-community/toolbar-android by using the below command:
yarn add #react-native-community/toolbar-android
Or
npm install --save #react-native-community/toolbar-android
Note: Both of these solutions are temporary and soonly this bug will be fixed and there is no need to install the toolbar-android package.
Prev Update
I update the package to the version "^7.0.0" on my project and still, the issue is remaining, so this solution is currently perseverance.
New Update
this issue is fixed on version "^7.1.0" and there is no need to install the #react-native-community/toolbar-android.

Update the library
react-native-vector-icons
to the latest version.

I had this problem too.
In my case, only works when I removed and added the package again with the latest version (7.0.0).
yarn remove react-native-vector-icons
yarn add react-native-vector-icons

Had this EXACT same error. All I had to do was install toolbar-android & voilà!
npm install --save #react-native-community/toolbar-android

Go the path \node_modules\native-base\node_modules\react-native-vector-icons\lib\toolbar-android.js
Replace import ToolbarAndroid from '#react-native-community/toolbar-android' to import {ToolbarAndroid} from './react-native';

I also got the same error after upgrading from version 6 to 7. The issue can be fixed simply by resetting the cache.
Please try npm start -- --reset-cache

do this:
rm -rf node_modules/
rm -rf package.lock.json
npm i
react-native start --reset-cache
from your project directory:)

Just Import it direct from react native it solves my problem
node_modules\react-native-vector-icons\lib\toolbar-android.js
import { ToolbarAndroid } from 'react-native';

Same issue, I solved it:
My environment:
RN: 0.61.5
Node: v12.18.3
OS: Windows 10 Pro
You can install react-native-vector-icons latest version (current 7.0.0).
And do not run auto-link (react-native link react-native-vector-icons)
Finally, running react-native start --reset-cache
Good luck.

First let's understand the standard convention used in package.json for packege's version.
So if you see ~1.0.2 it means to install version 1.0.2 or the latest patch version such as 1.0.4. If you see ^1.0.2 it means to install version 1.0.2 or the latest minor or patch version such as 1.1.0.
Now, coming to the issue.
The issue is caused because you are having a version of react-native-vector-icons which is giving you some trouble.
Check it's version by this command under your project directory:
npm list react-native-vector-icons --version \ is it 6.6.0 ??
No ?? . There is the problem. You need strictly 6.6.0 but you got something else.
Solution:
Delete node_modules directory under your project. Change the version of react-native-vector-icons in package.json to 6.6.0 (basically remove ^ to tell npm to get me exactly what I want. Nothing more, nothing less !)
Then do npm install !

The other alternative is to use expo's vector Icons. Something like this.
import { Ionicons } from "#expo/vector-icons".
Then render your Icon like this;
<Ionicons
name="ios-exit-outline"
color={colors.danger}
size={28}
style={{ marginRight: -15 }}
/>

Edit this file node_modules\react-native-vector-icons\lib\toolbar-android.js
remove 'import ToolbarAndroid from '#react-native-community/toolbar-android';'
edit return null

for this case you have not toolbar-android in your modules file and as friends saying you can fix it by this command
windows users:
npm install --save #react-native-community/toolbar-android
Mac users:
yarn add #react-native-community/toolbar-android
But IN GENERAL: I wanna tell you an experience for you guys whenever you encounter with this kind of errors that start with "Unable to resolve module" .
if you have a look to the error we have a problem with the module that system is telling us.
if you have not that module . you can install it with the commands
Windows users:
npm install --save THE MODULE(attention: THE MODULE IS THE NAME OF PACKAGES OR MODULES that u need to install)
and Mac users:
yarn add THE MODULE(attention: THE MODULE IS THE NAME OF PACKAGES OR MODULES that u need to install)
for example lets look at this error:
error Unable to resolve module `#react-native-community/slider` from `App.js`: #react-native-community/slider could not be found within the project.
as you can see error is telling us this module could not be found within our project.
so we need install it with this command:
for windows programmers:
npm install --save #react-native-community/slider
and for mac programmers:
yarn add #react-native-community/slider
that's all.
I hope you understand me clearly and do not have problem with unable to resolve module errors and my command be useful for you.
best regards
Mehrad Karampour (MEH)

Problem with the command "npm install fs"

I am not used to work with Linux, so maybe this is a silly question. In the lab that I am working on, I am asked to run the command "npm install fs" to read/write files.
But here is the error that i have and I don't know how to solve it, i couldn't find similar problems too.
PS: I am working on Ubuntu 17.10.

fs is a module that doesn't have to be installed. It comes part of node.js core so you only need to require it in your code.
Instead of running npm install fs --save, just add the following line in the file you're wanting to use it in:
const fs = require('fs');
Here are the docs: https://nodejs.dev/the-nodejs-fs-module
However, to address your question, the error message your receiving is likely due to the fact that:
You don't have a package.json in your project
You are not in the correct directory when running npm install ... and therefore it cannot find your package.json.
I believe your mistake is that you skipped the part where you initialize your npm repository (which generates your package.json).
To initialize an npm repo, do the following:
Navigate to your project root directory
Run npm init and follow the instructions if when prompted.

Webpack - dependency not found

I just started using Laravel Mix which is using webpack. I'm having some issues resolving dependencies.
I tried to install l20n with npm install l20n, added it to my project by adding require('l20n'); and then I ran npm run dev only to be told the following:
ERROR Failed to compile with 1 errors
This dependency was not found:
* fs in ./~/l20n/dist/bundle/node/l20n.js
Alright, so I figured I had to install fs too, issuing npm install fs and then I ran npm run dev again, but I get the exact same message. What am I doing wrong?

Ok, I checked out the source and I think I know what the issue is. The lib you are using is supposed to run in a node environment.
So, in your webpack configuration add this:
target: 'node'
For more info on targets see this

Uncaught Error: Module did not self-register

I try to use node-vlc with nw.js (v0.12.0-alpha2). When i launch my app without nw.js it works, but when i launch it with nw.js i got an error:
Uncaught Error: Module did not self-register.", source: /home/alexis/Bureau/dev/jukebox/node_modules/vlc/node_modules/ffi/node_modules/bindings/bindings.js (84)
I tried some commands with nw-gyp but it couldn't help me.
I am on Ubuntu 14, 64-bit.

If you've upgraded node then npm rebuild might fix this for you

For me:
rm -r node_modules then
npm install

I had a similar issue with another product and my fix was to change the version of node I was using. I was using 0.12.0 and changed back to 0.10.26.
Personally, I use NVM to handle node version changing. With NVM installed it's as simple as running
nvm use 0.10.26
Or setting the default version to 0.10.26
nvm alias default 0.10.26
Hopefully this helps you out - our issues came from different products but the solution may be the same.

I had similar problem.
/Users/user/NodeAddons/bridge/node_modules/bindings/bindings.js:83
Error: Module did not self-register.
In my case I was doing a C/C++ Add-on, and I had forgotten to export the add-on, in my main.cc was missing the code below:
void Init(v8::Handle<v8::Object> exports) {
NODE_SET_METHOD(exports, "method", method);
}
NODE_MODULE(method, Init);
Hope this helps others!
Thanks :)

I've add the same issue because I installed to modules as sudo...
Removing the node modules folder and reinstalling as normal user fixed it.

For me npm rebuild or npm update didn't work. I had to remove the node_modules folder and run npm install to install them again.

I once had this problem when creating a multi-file c++ addon. In my binding.gyp file I had:
"sources": ["src/*.cc", "src/*.h" ]
And my project contained several *.cc files. However, the NODE_MODULE() macro was called only on one file which imported the rest of the files. But node expects that it is called on the frist *.cc file listed in sources. So I had to change sources to explicitly add that file to the beginning

For me, running npm update worked

I was getting an internal error: Module did not self-register.
Deleted the node_modules folder
ran npm install
It worked just fine.

I had this error with Snappy. Was using Node 11. Checked Snappy's NPM page https://www.npmjs.com/package/snappy where they listed which versions of node they supported.
Deleting node_modules folder rm -rf node_modules and then reinstalling using the correct version of Node resolved it.
One of the versions they supported on Linux at the time of this writing was Node version 12.
nvm deactivate 11
nvm uninstall 11
nvm install 12
nvm use 12
Problem solved
Another cause of this problem: if you're using pm2, then after upgrading node you may need to reinstall pm2. Test whether pm2 is the issue by running your app
without pm2 node server.js
then with pm2: pm2 start server.js.
Proper way to update PM2 after updating Node.js

I had this same issue with 0.12 and io.js 1.3.0, reverting to Node.js 0.10 fixed the issue.

Rebuild your C++ add-ons.
Did you encounter something like this?
Module did not self-register: '…\node_modules\#u4\opencv4nodejs\build\Release\opencv4nodejs.node
It’s likely that you have just updated your Node.js. Once you updated your Node.js, you need to rebuild your C++ add-ons, Node.js packages written in C++.
Why
When you build Node.js’ C++ add-ons, they get compiled into require-able .node files and linked to the currently installed Node.js ABI library, which is not compatible with other versions of it. Your packages were built only compatible with the specific version of Node.js.
How
Firstly, try npm rebuild. If your C++-add-on-based packages have a build script, it’ll do. If it doesn’t, you need to manually build your C++ native add-on packages. Do again what you did when you were installing such packages. Refer to the building instructions in the packages’ documentations to rebuild them. Or try reinstalling (npm install) them.

I had the same problem. My script that was referencing a global reference script had an invalid reference. I took off that invalid reference and the error was gone. My error message had no indication of that particular invalid reference which made it harder to debug. But 'Uncaught Error: Module did not self-register' was the message I was getting.
This also happen in my other project. For some reason, it wouldn't recognize the reference path if one of the characters are uppercase. Even thought, the upper-casing was the correct spelling of the path.

I had this issue while setting up my Cypress project.
I found out the issue was caused because Cypress uses node from its bundle version by default (which was version 8.0 in my case) , whilst the package I wanted to use required the node version to be 10 or higher.
I did have node 12.0 installed on my machine but since cypress was not using that I had to add the line shown below in the settings file (cypress.json) to set the value for 'nodeVersion' to 'system', to tell cypress explicitly to use the node version installed on my machine.
Add this line to your settings file:
**"nodeVersion": "system"**