diff --git a/app/build.gradle b/app/build.gradle
index 89fd8cf98..810c0e601 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -46,9 +46,9 @@ ext {
 }
 
 dependencies {
-    implementation 'com.simplemobiletools:commons:3.14.5'
+    implementation 'com.simplemobiletools:commons:3.14.6'
     implementation 'com.theartofdev.edmodo:android-image-cropper:2.6.0'
-    implementation 'com.android.support:multidex:1.0.2'
+    implementation 'com.android.support:multidex:1.0.3'
     implementation 'com.google.code.gson:gson:2.8.2'
     implementation 'it.sephiroth.android.exif:library:1.0.1'
     implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.8'
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/DirectoryAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/DirectoryAdapter.kt
index a795756e5..20e7802d7 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/DirectoryAdapter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/DirectoryAdapter.kt
@@ -51,7 +51,7 @@ class DirectoryAdapter(activity: BaseSimpleActivity, var dirs: MutableList<Direc
         view?.dir_check?.beVisibleIf(select)
     }
 
-    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
         val layoutType = if (isListViewType) R.layout.directory_item_list else R.layout.directory_item_grid
         return createViewHolder(layoutType, parent)
     }
@@ -100,10 +100,10 @@ class DirectoryAdapter(activity: BaseSimpleActivity, var dirs: MutableList<Direc
 
     override fun getSelectableItemCount() = dirs.size
 
-    override fun onViewRecycled(holder: ViewHolder?) {
+    override fun onViewRecycled(holder: ViewHolder) {
         super.onViewRecycled(holder)
         if (!activity.isActivityDestroyed()) {
-            Glide.with(activity).clear(holder?.itemView?.dir_thumbnail!!)
+            Glide.with(activity).clear(holder.itemView?.dir_thumbnail!!)
         }
     }
 
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageFoldersAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageFoldersAdapter.kt
index e0d8aee5a..157ef989e 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageFoldersAdapter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageFoldersAdapter.kt
@@ -35,7 +35,7 @@ class ManageFoldersAdapter(activity: BaseSimpleActivity, var folders: ArrayList<
 
     override fun getSelectableItemCount() = folders.size
 
-    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int) = createViewHolder(R.layout.item_manage_folder, parent)
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = createViewHolder(R.layout.item_manage_folder, parent)
 
     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
         val folder = folders[position]
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageHiddenFoldersAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageHiddenFoldersAdapter.kt
index 095b7ca30..42ab5efe1 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageHiddenFoldersAdapter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/ManageHiddenFoldersAdapter.kt
@@ -37,7 +37,7 @@ class ManageHiddenFoldersAdapter(activity: BaseSimpleActivity, var folders: Arra
 
     override fun getSelectableItemCount() = folders.size
 
-    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int) = createViewHolder(R.layout.item_manage_folder, parent)
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = createViewHolder(R.layout.item_manage_folder, parent)
 
     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
         val folder = folders[position]
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
index 7b6477894..70dc22f94 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
@@ -57,7 +57,7 @@ class MediaAdapter(activity: BaseSimpleActivity, var media: MutableList<Medium>,
         view?.medium_check?.beVisibleIf(select)
     }
 
-    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
         val layoutType = if (isListViewType) R.layout.photo_video_item_list else R.layout.photo_video_item_grid
         return createViewHolder(layoutType, parent)
     }
@@ -107,10 +107,10 @@ class MediaAdapter(activity: BaseSimpleActivity, var media: MutableList<Medium>,
 
     override fun getSelectableItemCount() = media.size
 
-    override fun onViewRecycled(holder: ViewHolder?) {
+    override fun onViewRecycled(holder: ViewHolder) {
         super.onViewRecycled(holder)
         if (!activity.isActivityDestroyed()) {
-            val itemView = holder?.itemView
+            val itemView = holder.itemView
             visibleItemPaths.remove(itemView?.photo_name?.tag)
             Glide.with(activity).clear(itemView?.medium_thumbnail!!)
         }