Ionic serve doesnt work anymore (r.n is not a constructor)

I have a strange behavior of ionic serve…
I always get the following error message:

Runtime Error
r.n is not a constructor
TypeError: r.n is not a constructor
    at Object.<anonymous> (http://localhost:8100/build/vendor.js:1:115708)
    at e (http://localhost:8100/build/vendor.js:1:101)
    at Object.475 (http://localhost:8100/build/main.js:7659:72)
    at e (http://localhost:8100/build/vendor.js:1:101)
    at Object.<anonymous> (http://localhost:8100/build/vendor.js:1:50183)
    at Object.<anonymous> (http://localhost:8100/build/vendor.js:1:108597)
    at e (http://localhost:8100/build/vendor.js:1:101)
    at Object.5 (http://localhost:8100/build/main.js:7843:72)
    at e (http://localhost:8100/build/vendor.js:1:101)
    at Object.<anonymous> (http://localhost:8100/build/vendor.js:1:873932)
Ionic Framework: 3.9.2
Ionic App Scripts: 3.1.8
Angular Core: 5.0.3
Angular Compiler CLI: 5.0.3
Node: 8.9.2
OS Platform: macOS High Sierra
Navigator Platform: MacIntel
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36

In the console, i get the additional error

GET http://localhost:8100/assets/fonts/roboto-regular.woff2 404 (Not Found)

Funny thing is, roboto-regular.woff2 is there. If i open the url in safari, i can access this file.
Funny thing2: In chrome, i still see an old version of http://localhost:8100/build/main.css, in safarai its up to date

Sometimes the error shows up in safari as well, but when i do a reload, it works most of the time.
In chrome i have to reload at least a dozen times, until it works. But the error shows up again, as soon as i make a change in my code and livereload is triggered.

Anyone has an idea whats heppening?

best regards


if it sometimes work and then not, maybe it helps to delete content of www folder in your project and clear any cache in browsers.

If this not helps search for r.n, because maybe r.n is called as constroctur but is not a construtor, somthing like a new on a method, things without constructor etc…

Best regards, anna-liebt