Angular app is not building anymore. build-long.md was not found

Issue

After making a minor update to the @angular-devkit/build-angular package, the build script is not working anymore. When I start the build with ng build app --base-href /app/ --output-path ./dist/app/de/ --deployUrl /en/app/ --configuration=dev an unhandled exception occurs:

An unhandled exception occurred: File C:\Users\<User>\Projects\<project>\angular\node_modules\@angular\cli\commands\build-long.md was not found while constructing the subcommand build.

After that I upgraded to the newest version 9 and re-installed the complete package with the same result. I also updated @angular/cli and @angular/compiler-cli which changed nothing. I removed the node_modules folder and re-installed everything. The problem persists...

Then I downgraded @angular-devkit/build-angular to version 0.802.2. (which was lower than the version we used before the upgrade) and exact the same problem.

I looked into the package and there is no build-long.md file. Why is this problem occuring? Can anyone help?

Solution

I finally found the problem. Yarn creates a .yarnclean file when cleaning the node_modules and there it excludes .md files from the installed packages.

So I had to remove the .md entry from the yarnclean file and install all packages again and it worked.

Answered By - Florian Leitgeb