Is it correct to say "a new" or "the new"? [closed]

Context, context, context!

The basic rule is that you use the if you expect your hearers/readers to know which one you're talking about.

So if you've already mentioned this new version, or it's part of the general knowledge you share with your hearers/readers, you can use the. But when you introduce a new entity into the discourse, you use a.

I know the program's slow right now, but I'm writing a new version. The new version will be released in May.

You may also use the to speak of a new entity if you distinguish it immediately, within the same noun phrase.

We're working on three new versions. The version I am working on is targeted to social media users.

The use of the definite or indefinite article depends on the meaning you would like to express. Both cases are possible in different situations.

a new version is the case of the noun modified with the descriptive adjective, therefore, the indefinite article can be chosen.

the new version -you are telling the reader which thing we are talking about. You are referring to the particular version of the program.