diff --git a/WordPress/src/main/java/org/wordpress/android/ui/debug/DebugSettingsViewModel.kt b/WordPress/src/main/java/org/wordpress/android/ui/debug/DebugSettingsViewModel.kt
index 754d291afd70..395daf3a1573 100644
--- a/WordPress/src/main/java/org/wordpress/android/ui/debug/DebugSettingsViewModel.kt
+++ b/WordPress/src/main/java/org/wordpress/android/ui/debug/DebugSettingsViewModel.kt
@@ -132,7 +132,6 @@ class DebugSettingsViewModel
         return when (this) {
             FeatureFlagConfigDao.FeatureFlagValueSource.BUILD_CONFIG -> "Local value"
             FeatureFlagConfigDao.FeatureFlagValueSource.REMOTE -> "Remote Value"
-            else -> null
         }
     }
 
diff --git a/WordPress/src/main/java/org/wordpress/android/ui/mysite/MySiteFragment.kt b/WordPress/src/main/java/org/wordpress/android/ui/mysite/MySiteFragment.kt
index 7ef9e636cfe2..8010249aafeb 100644
--- a/WordPress/src/main/java/org/wordpress/android/ui/mysite/MySiteFragment.kt
+++ b/WordPress/src/main/java/org/wordpress/android/ui/mysite/MySiteFragment.kt
@@ -212,9 +212,9 @@ class MySiteFragment : Fragment(R.layout.my_site_fragment),
     }
 
     override fun onConfirm(result: Bundle?) {
-        val task = result?.getSerializableCompat(
+        val task = result?.getSerializableCompat<QuickStartStore.QuickStartTask>(
             QuickStartFullScreenDialogFragment.RESULT_TASK
-        ) as? QuickStartStore.QuickStartTask
+        )
         task?.let { viewModel.onQuickStartTaskCardClick(it) }
     }
 
diff --git a/WordPress/src/main/java/org/wordpress/android/ui/stats/refresh/StatsFragment.kt b/WordPress/src/main/java/org/wordpress/android/ui/stats/refresh/StatsFragment.kt
index f2a173cc2283..5897f133c42f 100644
--- a/WordPress/src/main/java/org/wordpress/android/ui/stats/refresh/StatsFragment.kt
+++ b/WordPress/src/main/java/org/wordpress/android/ui/stats/refresh/StatsFragment.kt
@@ -81,9 +81,9 @@ class StatsFragment : Fragment(R.layout.stats_fragment), ScrollableViewInitializ
             WeakReference<StatsPullToRefreshListener.PullToRefreshEmitterListener>? = null
 
     override fun setPullToRefreshReceiver(
-        pullToRefreshEmitterListener: StatsPullToRefreshListener.PullToRefreshEmitterListener
+        emitterListener: StatsPullToRefreshListener.PullToRefreshEmitterListener
     ) {
-        currentStatsPullToRefreshListener = WeakReference(pullToRefreshEmitterListener)
+        currentStatsPullToRefreshListener = WeakReference(emitterListener)
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 7f6bda2bce6c..c9bf9982e381 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -83,10 +83,10 @@ json-path = '2.9.0'
 jsoup = '1.20.1'
 junit = '4.13.2'
 kotlin-compile-testing = '1.6.0'
-kotlin-main = '2.0.21'
+kotlin-main = '2.1.21'
 kotlinx-coroutines = '1.10.2'
 kotlinx-kover = '0.7.6'
-ksp = '2.0.21-1.0.28'
+ksp = '2.1.21-2.0.1'
 mockito-android = '5.18.0'
 mockito-kotlin = '4.1.0'
 mpandroidchart = 'v3.1.0'
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/ListOrder.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/ListOrder.kt
index ec8061f6b9c0..77b70276d50d 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/ListOrder.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/ListOrder.kt
@@ -7,7 +7,7 @@ enum class ListOrder(val value: String) {
     DESC("DESC");
     companion object {
         fun fromValue(value: String): ListOrder? {
-            return values().firstOrNull { it.value.toLowerCase(Locale.ROOT) == value.toLowerCase(Locale.ROOT) }
+            return values().firstOrNull { it.value.lowercase(Locale.ROOT) == value.lowercase(Locale.ROOT) }
         }
     }
 }
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/PostListDescriptor.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/PostListDescriptor.kt
index 5f8296f62f2a..03ab6dd36f46 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/PostListDescriptor.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/list/PostListDescriptor.kt
@@ -105,7 +105,7 @@ enum class PostListOrderBy(val value: String) {
 
     companion object {
         fun fromValue(value: String): PostListOrderBy? {
-            return values().firstOrNull { it.value.toLowerCase(Locale.ROOT) == value.toLowerCase(Locale.ROOT) }
+            return values().firstOrNull { it.value.lowercase(Locale.ROOT) == value.lowercase(Locale.ROOT) }
         }
     }
 }
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/notification/NotificationModel.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/notification/NotificationModel.kt
index 210d9d3bd39d..610c7c8480c5 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/notification/NotificationModel.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/model/notification/NotificationModel.kt
@@ -62,7 +62,7 @@ data class NotificationModel(
                 return if (type.isEmpty()) {
                     NONE
                 } else {
-                    reverseMap[type.toUpperCase(Locale.US)] ?: UNKNOWN
+                    reverseMap[type.uppercase(Locale.US)] ?: UNKNOWN
                 }
             }
         }
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/network/rest/wpcom/site/BooleanTypeAdapter.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/network/rest/wpcom/site/BooleanTypeAdapter.kt
index 4a71d07772e6..c8c51a4485ce 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/network/rest/wpcom/site/BooleanTypeAdapter.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/network/rest/wpcom/site/BooleanTypeAdapter.kt
@@ -16,7 +16,7 @@ internal class BooleanTypeAdapter : JsonDeserializer<Boolean?> {
         return when {
             jsonPrimitive.isBoolean -> jsonPrimitive.asBoolean
             jsonPrimitive.isNumber -> jsonPrimitive.asNumber.toInt() == 1
-            jsonPrimitive.isString -> TRUE_STRINGS.contains(jsonPrimitive.asString.toLowerCase(
+            jsonPrimitive.isString -> TRUE_STRINGS.contains(jsonPrimitive.asString.lowercase(
                 Locale.getDefault()
             ))
             else -> false
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/NotificationStore.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/NotificationStore.kt
index b80f4cda65d8..cbbcab67c155 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/NotificationStore.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/NotificationStore.kt
@@ -74,7 +74,7 @@ class NotificationStore @Inject constructor(
 
         companion object {
             private val reverseMap = values().associateBy(DeviceRegistrationErrorType::name)
-            fun fromString(type: String) = reverseMap[type.toUpperCase(Locale.US)] ?: GENERIC_ERROR
+            fun fromString(type: String) = reverseMap[type.uppercase(Locale.US)] ?: GENERIC_ERROR
         }
     }
 
@@ -147,7 +147,7 @@ class NotificationStore @Inject constructor(
 
         companion object {
             private val reverseMap = values().associateBy(NotificationErrorType::name)
-            fun fromString(type: String) = reverseMap[type.toUpperCase(Locale.US)] ?: GENERIC_ERROR
+            fun fromString(type: String) = reverseMap[type.uppercase(Locale.US)] ?: GENERIC_ERROR
         }
     }
 
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/PageStore.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/PageStore.kt
index 2e1e8b51277b..4242074a3062 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/PageStore.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/PageStore.kt
@@ -83,8 +83,8 @@ class PageStore @Inject constructor(
     suspend fun search(site: SiteModel, searchQuery: String): List<PageModel> =
             coroutineEngine.withDefaultContext(AppLog.T.POSTS, this, "search") {
                 getPagesFromDb(site).filter {
-                    it.title.toLowerCase(Locale.ROOT)
-                            .contains(searchQuery.toLowerCase(Locale.ROOT))
+                    it.title.lowercase(Locale.ROOT)
+                            .contains(searchQuery.lowercase(Locale.ROOT))
                 }
             }
 
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/QuickStartStore.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/QuickStartStore.kt
index 1fc2d7e52165..fbe5579353ee 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/QuickStartStore.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/QuickStartStore.kt
@@ -11,6 +11,7 @@ import org.wordpress.android.fluxc.store.QuickStartStore.QuickStartTaskType.CUST
 import org.wordpress.android.fluxc.store.QuickStartStore.QuickStartTaskType.GET_TO_KNOW_APP
 import org.wordpress.android.fluxc.store.QuickStartStore.QuickStartTaskType.GROW
 import org.wordpress.android.util.AppLog
+import java.io.Serializable
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -19,7 +20,7 @@ class QuickStartStore @Inject constructor(
     private val quickStartSqlUtils: QuickStartSqlUtils,
     dispatcher: Dispatcher
 ) : Store(dispatcher) {
-    interface QuickStartTask {
+    interface QuickStartTask: Serializable {
         val string: String
         val taskType: QuickStartTaskType
         val order: Int
diff --git a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/SiteStore.kt b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/SiteStore.kt
index c4a25ef41964..4d4622f6e2d8 100644
--- a/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/SiteStore.kt
+++ b/libs/fluxc/src/main/java/org/wordpress/android/fluxc/store/SiteStore.kt
@@ -1012,7 +1012,7 @@ open class SiteStore @Inject constructor(
             private const val SITE = "SITE"
             @JvmStatic fun fromString(string: String): NewSiteErrorType {
                 if (!TextUtils.isEmpty(string)) {
-                    val siteString = string.toUpperCase(Locale.US).replace(BLOG, SITE)
+                    val siteString = string.uppercase(Locale.US).replace(BLOG, SITE)
                     for (v in values()) {
                         if (siteString.equals(v.name, ignoreCase = true)) {
                             return v