Cannot access UI of dockerized, unsecured Nifi: An unexpected error has occured

  apache-nifi, docker, windows

I want to access a dockerized, unsecured Nifi instance from the host:

docker run --name nifi -p 8080:8080 -d apache/nifi:latest

(The standard command from

Now when I open http://localhost:8080/nifi I do see for a short moment
the loading animation of nifi. However, then I get:

An unexpected error has occured (plus some wrongly decoded characters)

The Chrome console has three 409 errors:

In the nifi logs there are absolutely no error messages.
One can also use the Rest API to set up flows etc. So otherwise
nifi seems to be working properly.
Does anyone has an idea? Could this be a firewall issue?

My host system is Windows 10 with firewall managed by my company, so
unfortunately I cannot change anything here.

Any hint is appreciated a lot. Many thanks!

Source: Windows Questions