Selling under Generic Brand?

Hi everyone,

I have been reading and gathering information. I am a new seller and I wanted to confirm few things.

Is selling under Generic brand safe? I have heard of hijackers. I have purchased GTIN code from GS1 website but I keep getting ‘SKU does not match ASIN error (8572). Does GTIN code matter if there is no brand? There is Generic –> Brand Approval –> Brand Registry. I believe private labeling falls under brand approval and if business takes off, one can trademark and register brand?

Thank you.