Dostava je postala problem.

Dostava usually means delivery, especially the delivery of food, packages, or goods.

In this sentence, it most likely means:

• the delivery service
• the process of delivery
• the general issue of delivery in some situation

So it is not necessarily one single delivery, but delivery as a broader matter.

Je is the 3rd person singular present form of biti (to be), and here it helps form the perfect tense.

So:

• je postala = became / has become

This is a very common Serbian past-tense structure:

• subject + je + past participle

Example:

• Ona je došla. = She came / has come.

Because postala must agree with the subject dostava.

Dostava is:

• singular
• feminine

In Serbian, the past participle agrees with the subject in gender and number.

So:

• masculine singular: postao
• feminine singular: postala
• neuter singular: postalo

Because dostava is feminine, the correct form is postala.

The base form is postati, which means to become.

So:

• postati = to become
• postala = became / has become, feminine singular

This verb is very common when talking about a change of state:

• Situacija je postala ozbiljna. = The situation became serious.

It is the perfect tense in Serbian.

In English, depending on context, it can often be translated as:

• became
• has become

Serbian perfect tense often covers both of those English possibilities, so the exact English translation depends on context.

Because problem is a predicate noun here, and it keeps its own natural gender.

• dostava is feminine
• problem is masculine

That is completely normal.

The noun after postati does not have to agree in gender with the subject. It simply names what something has become.

So:

• Dostava je postala problem.
  means that delivery has become a problem.

After postati (to become), Serbian normally uses the nominative for the noun that describes what something became.

So:

• postati problem
• postati lekar
• postati rešenje

That is why you see problem, not a different case form.

Because Serbian does not have articles like English a, an, and the.

So English says:

• a problem
• the problem

But Serbian simply says:

• problem

The exact meaning is understood from context.

Because je is a clitic. Serbian clitics usually go in or near the second position in the sentence.

So the neutral order is:

• Dostava je postala problem.

This is very natural Serbian word order.

English speakers often expect the verb to behave more freely, but short forms like je have special placement rules in Serbian.

Yes, but the neutral, most natural version is:

• Dostava je postala problem.

Serbian word order is more flexible than English, so other orders are possible for emphasis, contrast, or style. However, not all alternatives sound equally natural in every context.

For a learner, the safest choice is the sentence as given.

It can mean either, depending on context.

Serbian je postala is a perfect form that often corresponds to:

• simple past in English: became
• present perfect in English: has become

So if the context is about a recent development with present relevance, English may prefer has become a problem.
If the context is just telling a past event, English may prefer became a problem.

Yes, but that means something slightly different.

• Dostava je postala problem. = delivery became / has become a problem
• Dostava postaje problem. = delivery is becoming a problem

So:

• je postala describes a change that has already happened
• postaje describes a change that is happening now or developing

Yes. Postati is a perfective verb.

That matters because perfective verbs usually describe:

• a completed change
• a result

So postala fits well here, because the sentence says that delivery reached a new state: it became a problem.

The imperfective partner is postajati, which would suggest an ongoing or repeated process of becoming. In this sentence, postati is the natural choice.