Could not find com.android.tools.build:gradle:4.0.1 ( or any version )

I think the solution will only work in Iran . If you know that 's working out of Iran , please note in the comments .

why would a proxy be necessary? There have been a number of technology-related sanctions against Iran.

go to -> File | Settings | Appearance & Behavior | System Settings | HTTP Proxy, and choose -> manual proxy configuration. set host name: fodev.org and set port number: 8118 . now you must find gradle.properties file. that must be in: Windows: C:\Users\YOURUSERNAME.gradle\gradle.properties OR for Linux: ~/.gradle/gradle.properties . if does't exist, create that yourself. and copy this :

systemProp.http.proxyHost=fodev.org
systemProp.http.proxyPort=8118
systemProp.http.nonProxyHosts=*.jitpack.io, *.maven.org
systemProp.https.proxyHost=fodev.org
systemProp.https.proxyPort=8118
systemProp.https.nonProxyHosts=*.jitpack.io, *.maven.org

now you can sync project.

IMPORTANT : after install build.gradle 4.0.1 (or every version), back this settings to before and remove codes

Deleting and reinstalling my node modules seemed to work for me

rm -rf node_modules
yarn install