Expected start of the array '[', but had 'EOF' instead

Question

I'm trying to fetch data from API. My app crashes and it gives me this error:

kotlinx.serialization.json.internal.JsonDecodingException: Expected start of the array '[', but had 'EOF' instead JSON input: { "generated_at": "2022-05-20T10:29:36+00:00", "summaries": [] }

I searched for a solution and found a website that corrects any errors in a json response, but unfortunately it didn't work.

This is my json response (Not the whole response, just one item):

{
"generated_at": "2022-05-20T09:40:26+00:00",
"schedules": [
    {
        "sport_event": {
            "id": "sr:sport_event:27751052",
            "start_time": "2021-08-13T19:00:00+00:00",
            "start_time_confirmed": true,
            "sport_event_context": {
                "sport": {
                    "id": "sr:sport:1",
                    "name": "Soccer"
                },
                "category": {
                    "id": "sr:category:1",
                    "name": "England",
                    "country_code": "ENG"
                },
                "competition": {
                    "id": "sr:competition:17",
                    "name": "Premier League",
                    "gender": "men"
                },
                "season": {
                    "id": "sr:season:83706",
                    "name": "Premier League 21\/22",
                    "start_date": "2021-08-13",
                    "end_date": "2022-05-22",
                    "year": "21\/22",
                    "competition_id": "sr:competition:17"
                },
                "stage": {
                    "order": 1,
                    "type": "league",
                    "phase": "regular season",
                    "start_date": "2021-08-13",
                    "end_date": "2022-05-22",
                    "year": "21\/22"
                },
                "round": {
                    "number": 1
                },
                "groups": [
                    {
                        "id": "sr:league:56620",
                        "name": "Premier League 21\/22"
                    }
                ]
            },
            "coverage": {
                "type": "sport_event",
                "sport_event_properties": {
                    "lineups": true,
                    "extended_player_stats": true,
                    "extended_team_stats": true,
                    "lineups_availability": "pre",
                    "ballspotting": true,
                    "commentary": true,
                    "fun_facts": true,
                    "goal_scorers": true,
                    "scores": "live",
                    "game_clock": true,
                    "deeper_play_by_play": true,
                    "deeper_player_stats": true,
                    "deeper_team_stats": true,
                    "basic_play_by_play": true,
                    "basic_player_stats": true,
                    "basic_team_stats": true
                }
            },
            "competitors": [
                {
                    "id": "sr:competitor:50",
                    "name": "Brentford FC",
                    "country": "England",
                    "country_code": "ENG",
                    "abbreviation": "BRE",
                    "qualifier": "home",
                    "gender": "male"
                },
                {
                    "id": "sr:competitor:42",
                    "name": "Arsenal FC",
                    "country": "England",
                    "country_code": "ENG",
                    "abbreviation": "ARS",
                    "qualifier": "away",
                    "gender": "male"
                }
            ],
            "venue": {
                "id": "sr:venue:53349",
                "name": "Brentford Community Stadium",
                "capacity": 17250,
                "city_name": "London",
                "country_name": "England",
                "map_coordinates": "51.4907295,-0.2891696",
                "country_code": "ENG"
            }
        },
        "sport_event_status": {
            "status": "closed",
            "match_status": "ended",
            "home_score": 2,
            "away_score": 0,
            "winner_id": "sr:competitor:50",
            "period_scores": [
                {
                    "home_score": 1,
                    "away_score": 0,
                    "type": "regular_period",
                    "number": 1
                },
                {
                    "home_score": 1,
                    "away_score": 0,
                    "type": "regular_period",
                    "number": 2
                }
            ]
        }
    }]}

This is some of the data classes:

    @Serializable
data class Schedules(
    @SerialName("generated_at")
    val generatedAt: String,
    @SerialName("schedules")
    val schedules: List<Schedule>
)



    @Serializable
data class Schedule(
    @SerialName("sport_event")
    val sportEvent: SportEvent,
    @SerialName("sport_event_status")
    val sportEventStatus: SportEventStatus
)



@Serializable
data class SportEvent(
    @SerialName("competitors")
    val competitors: List<Competitor>,
    @SerialName("coverage")
    val coverage: Coverage,
    @SerialName("id")
    val id: String,
    @SerialName("sport_event_context")
    val sportEventContext: SportEventContext,
    @SerialName("start_time")
    val startTime: String,
    @SerialName("start_time_confirmed")
    val startTimeConfirmed: Boolean,
    @SerialName("venue")
    val venue: Venue
)

Logcat:

E/AndroidRuntime: FATAL EXCEPTION: DefaultDispatcher-worker-1
Process: com.example.a356scoresclone, PID: 19000
kotlinx.serialization.json.internal.JsonDecodingException: Expected start of the array '[', but had 'EOF' instead
JSON input: {
    "generated_at": "2022-05-20T10:47:43+00:00",
    "summaries": []
}
    at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:24)
    at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:32)
    at kotlinx.serialization.json.internal.JsonLexer.fail(JsonLexer.kt:493)
    at kotlinx.serialization.json.internal.JsonLexer.fail(JsonLexer.kt:215)
    at kotlinx.serialization.json.internal.JsonLexer.unexpectedToken(JsonLexer.kt:198)
    at kotlinx.serialization.json.internal.JsonLexer.consumeNextToken(JsonLexer.kt:188)
    at kotlinx.serialization.json.internal.StreamingJsonDecoder.beginStructure(StreamingJsonDecoder.kt:37)
    at kotlinx.serialization.internal.AbstractCollectionSerializer.merge(CollectionSerializers.kt:29)
    at kotlinx.serialization.internal.AbstractCollectionSerializer.deserialize(CollectionSerializers.kt:43)
    at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)
    at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:32)
    at kotlinx.serialization.json.Json.decodeFromString(Json.kt:100)
    at com.jakewharton.retrofit2.converter.kotlinx.serialization.Serializer$FromString.fromResponseBody(Serializer.kt:30)
    at com.jakewharton.retrofit2.converter.kotlinx.serialization.DeserializationStrategyConverter.convert(DeserializationStrategyConverter.kt:11)
    at com.jakewharton.retrofit2.converter.kotlinx.serialization.DeserializationStrategyConverter.convert(DeserializationStrategyConverter.kt:7)
    at retrofit2.OkHttpCall.parseResponse(OkHttpCall.java:243)
    at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:153)
    at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:520)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:923)
    Suppressed: kotlinx.coroutines.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@34fb196, Dispatchers.IO]

Edit: I've just realized that I have the wrong endpoint. So instead of writing "schedules.json" I have "summaries.json". But still I have a similar error:

    kotlinx.serialization.json.internal.JsonDecodingException: Expected start of the array '[', but had 'EOF' instead
JSON input: .....match_status": "not_started"
            }
        }
    ]
}

Answer 1

I know this doesn't directly answer the question mentioned above but I am posting this here as I had a similar issue during testing on Ktor Server.

This was the error I got.

kotlinx.serialization.json.internal.JsonDecodingException: Expected start of the object '{', but had 'EOF' instead

EOF in JSON just means End of File

This was my code:

fun testFun() = testApplication { ....
val response = client.get("/boruto/heroes")
val actual = Json.decodeFromString<ApiResponse>(response.content.toString())
....
}

I realized the problem occurred as I was using reponse.content instead of response.body.

val actual = Json.decodeFromString<T>(response.content.toString())

I changed it to this and the test eventually passed

val actual = Json.decodeFromString<T>(response.body())

I'm leaving this here in case someone encounters the same issue.