[pluto9]

It would mean completely rewriting your UI. Angular 2+ is a completely different framework from 1.x.

2+ shouldn't have even used the Angular name IMO.

[eitland]

FWIW some tools including an official one from Google exist to help in migration.

I've worked with both 1.3-1.5 as well as 2, 4 and 5 and if I inherited a 1.x codebase I'd rewrite it, if necessary one piece at the time.