diff --git a/STNetwork/src/commonMain/kotlin/com/infomaniak/multiplatform_swisstransfer/network/requests/UploadRequest.kt b/STNetwork/src/commonMain/kotlin/com/infomaniak/multiplatform_swisstransfer/network/requests/UploadRequest.kt
index 9a7c0c41..f5954272 100644
--- a/STNetwork/src/commonMain/kotlin/com/infomaniak/multiplatform_swisstransfer/network/requests/UploadRequest.kt
+++ b/STNetwork/src/commonMain/kotlin/com/infomaniak/multiplatform_swisstransfer/network/requests/UploadRequest.kt
@@ -36,11 +36,16 @@ import io.ktor.http.contentType
 import io.ktor.http.isSuccess
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.encodeToJsonElement
 
 internal class UploadRequest(json: Json, httpClient: HttpClient) : BaseRequest(json, httpClient) {
 
     suspend fun initUpload(initUploadBody: InitUploadBody): InitUploadResponseApi {
-        return post(url = createUrl(ApiRoutes.initUpload), initUploadBody)
+        val nullableJson = Json(json) {
+            explicitNulls = false
+        }
+        val encodedInitUploadBody = nullableJson.encodeToJsonElement(initUploadBody)
+        return post(url = createUrl(ApiRoutes.initUpload), encodedInitUploadBody)
     }
 
     suspend fun verifyEmailCode(verifyEmailCodeBody: VerifyEmailCodeBody): AuthorEmailToken {