Identical Retrofit call throws Unable to create call adapter error while the other one works

Question

I am trying to setup Paging 3 with Retrofit and I am unable to get past this call.

val response = redditAPI.getSubreddits(mBearer, mWhere, position, params.loadSize)

The getSubreddits method is this

    @GET("/subreddits/mine/{where}")
    fun getSubreddits(
            @Header("Authorization") bearer: String,
            @Path("where") where: String,
            @Query("after") after: String,
            @Query("count") count: Int
    ): SubredditResponse

I have checked with a debugger and the inputs are exactly what I want.

A friend implemented this

    @GET("{subreddit}/{filter}")
    suspend fun getPostList(
            @Path("subreddit") subreddit: String,
            @Path("filter") filter: String,
            @Query("after") after: String,
            @Query("count") count: Int,
            @Header("Authorization") bearer: String
    ): Listing

and he used this call

val response = redditAPI.getPostList(mSubreddit, mFilter, position, params.loadSize, mBearer)

and it works perfectly. I read that this error is related to the fact that Call should be used as a return type but that is the way Paging 3 is set up with Retrofit and I can see no reason why it won't work. It's probably something stupid but I really cannot see what it is. The inputs from the other levels above this call are also correct, also checked with a debugger and all seem well.

Thank you in advance.

Answer 1

So, the problem was the missing suspend keyword before declaring the function. The Retrofit error was not helpful at all and I have little experience with Kotlin, so I had no idea the suspend keyword was that important. Lesson learned.