This happened also to me upgrading from 0.63 to 0.64. After trying all solutions I followed a solution moving the folder to a directory where the path contain no spaces and it works and build the app successfully.

Solution to React Native 0.64 build fail

In order for this to work properly follow these steps:

• If you previously installed a global react-native-cli package, please remove it as it may cause unexpected issues (i.e. npm uninstall -g react-native-cli)
• Move the project folder in a path with no spaces (i.e. ~/sub folder name/ReactNativeApp won't work till you have spaces in the path, so move in a path like ~/folder/ReactNativeApp)
• Then cd into the project folder and upgrade react native to the latest version with npx react-native upgrade and resolve conflicts if any
• After upgrading remove the node_modules folder and the yarn.lock from the root and the podfile.lock and Pods folder from ios subfolder
• Then cd back to the root and run yarn install && npx pod-install
• Now run again your app in Xcode or your IDE and it works

Crazy and absurd that a space in the path-name could cause this issue