Working permit from one EU country to work in an another EU country as self-employed

[newNomad]

So let's suppose I am a work residence permit holder of EU country A, as owner/self-employed of my own individual company
I need to work at client onsite in EU coutry B.
Can I just uproot and go work onsite in the country B, invoicing calmly from my entity in country A? So it is a contractor relationship, no slave (employed) relationship.
If anyone asks me anything I already have a permit from country A and can move freely anywhere in Schengen.

If this wont work, why? And what is the solution, given that I absolutely cannot renounce the permit of country A and need be resident in the country A since I have a registered and active business in A.
Someone explains how all this bull work in EU, I am sick of it's bureaucracy and red tape..

 

[Allisgood]

Typically only EU citizens have free movement rights between EU countries, not residency holders.

If you have a residence permit for country A you can only live in country A and are allowed to travel for tourism to country B.

Probably nobody will check if you live as a tourist, but if you want to officially move to B you won't be able to unless you get a new residence permit in B (and fulfil their requirements).