I'm trying to build my project but after push on gitlab it returns Error:

1 Answer
Your DBAL version is one that needs php 7 or higher. Pick another version that satisfies php 5.6, like DBAL 2.5.x
As a sidenote, this is why it is useful to make your local development environment resemble your production environment. php 7 has features that 5.6 doesn't and you WILL break your software 99.9% of the time.