Color name or number not recognized with User1-9

Question

When I run highlight User1 ctermbg=#505050 ctermfg=#d0d0d0 gui=italic, I get the following error.

E421: Color name or number not recognized: ctermbg=#505050 ctermfg=#d0d0d0 gui=italic

Answer 1

#xxyyzz is invalid value for ctermbg and ctermfg. It can only be used for guifg and guibg.

If your terminal has support for TrueColor then do set termguicolors and set guixx params instead.