We have copied a component into our project and added it to routing. The component uses the async template pipe.

When testing the route we get an error like this:

ERROR Error: Uncaught (in promise): Error: The pipe 'async' could not be found!
Error: The pipe 'async' could not be found!

And we are trying to figure out why that is happening.

Approach

In my particular case this happened because I forgot to declare the component in app.module.ts. I copied in in to the project, imported into app-routing.module.ts, and registered it in a route.

If I remove the pipe it still renders fine, thus making it particularly tricky to diagnose.

Also the application will compile and render fine without any warnings.