Serviser će nastaviti dijagnostiku osim ako nedostaje pristupna lozinka.

This is the future I tense in Serbian.

It is formed with:

• the short form of hteti (ću, ćeš, će, ćemo, ćete, će)
• plus the infinitive

So here:

• će = will
• nastaviti = to continue

Together, će nastaviti = will continue.

Because će is a clitic in Serbian. Clitics usually stand in the second position of the clause.

So:

• Serviser će nastaviti... is the normal order.
• Putting će first would usually sound wrong in this kind of sentence.

This second-position rule is very common in Serbian with forms like sam, si, je, smo, ste, su, ću, ćeš, će and similar short words.

This is about aspect.

• nastaviti = perfective
• nastavljati = imperfective

In this sentence, nastaviti is more natural because it presents the action as a single future step: the technician will continue the diagnostics.

If you used nastavljati, it would sound more like repeated, habitual, or ongoing continuation, which is not the main idea here.

So:

• će nastaviti dijagnostiku = will continue the diagnostics
• će nastavljati dijagnostiku would usually not fit this context as well

Because dijagnostiku is in the accusative case.

The verb nastaviti can take a direct object, and direct objects are often in the accusative.

Here:

• dijagnostika = nominative
• dijagnostiku = accusative

So the sentence is literally structured like:

• The technician will continue what?
• the diagnostics

That is why dijagnostiku is used.

Yes, that is also possible.

You can hear both patterns:

• nastaviti dijagnostiku
• nastaviti sa dijagnostikom

The first one uses a direct object. The second one uses sa + instrumental.

In technical or formal language, nastaviti dijagnostiku sounds very natural and efficient.

Osim ako means unless.

Literally, it is close to:

• except if

So:

• Serviser će nastaviti dijagnostiku osim ako nedostaje pristupna lozinka means
• The technician will continue the diagnostics unless the access password is missing

This is a very common way to express an exception to what will happen.

Because after expressions like ako and osim ako, Serbian often uses the present tense to refer to a future condition.

This is normal Serbian usage.

So even though the overall meaning is future:

• The technician will continue... unless...

the condition itself appears in the present:

• osim ako nedostaje...

This works much like:

• I’ll go if he comes where English also uses a present form in the condition.

Yes. Pristupna lozinka is the subject.

The verb nedostajati means something like:

• to be missing
• to be lacking
• to be absent

So the structure is not:

• someone is missing the password

It is:

• the password is missing

That is why:

• nedostaje is singular
• it agrees with pristupna lozinka

A more literal reading is:

• unless an access password is lacking / missing

Pristupna lozinka is in the nominative singular because it is the subject of nedostaje.

Both words agree with each other:

• pristupna = feminine singular nominative adjective
• lozinka = feminine singular nominative noun

So the phrase means:

• access password

This agreement is standard in Serbian: adjectives match the noun in gender, number, and case.

Because Serbian has no articles.

Unlike English, Serbian does not have separate words for:

• a / an
• the

So serviser can mean:

• a technician
• the technician

And pristupna lozinka can mean:

• an access password
• the access password

The exact meaning depends on context. In a sentence like this, the context usually makes it clear that a specific required password is meant.

Yes, Serbian word order is fairly flexible.

For example, you could also see:

• ... osim ako pristupna lozinka nedostaje

That would still be grammatical.

But osim ako nedostaje pristupna lozinka is a very natural order, especially when the speaker wants to present the condition first and then name what is missing.

So the original version sounds normal and idiomatic.

Serviser is a common Serbian word, and it usually means:

• service technician
• repair technician
• maintenance person

In technical contexts, it is very common.

Depending on the situation, it can refer to someone who:

• repairs equipment
• services machines
• performs diagnostics or maintenance

So in this sentence, serviser fits very naturally with dijagnostiku.