diff --git a/Adjust.podspec b/Adjust.podspec
index 1f8524cd5..15c1165fc 100644
--- a/Adjust.podspec
+++ b/Adjust.podspec
@@ -1,11 +1,11 @@
 Pod::Spec.new do |s|
   s.name           = "Adjust"
-  s.version        = "4.26.0"
+  s.version        = "4.26.1"
   s.summary        = "This is the iOS SDK of adjust. You can read more about it at http://adjust.com."
   s.homepage       = "https://github.com/adjust/ios_sdk"
   s.license        = { :type => 'MIT', :file => 'MIT-LICENSE' }
   s.author         = { "Christian Wellenbrock" => "welle@adjust.com" }
-  s.source         = { :git => "https://github.com/adjust/ios_sdk.git", :tag => "v4.26.0" }
+  s.source         = { :git => "https://github.com/adjust/ios_sdk.git", :tag => "v4.26.1" }
   s.ios.deployment_target = '6.0'
   s.tvos.deployment_target = '9.0'
   s.framework      = 'SystemConfiguration'
diff --git a/Adjust/ADJActivityHandler.h b/Adjust/ADJActivityHandler.h
index b3eac8f6f..2c797658b 100644
--- a/Adjust/ADJActivityHandler.h
+++ b/Adjust/ADJActivityHandler.h
@@ -23,8 +23,6 @@
 @property (nonatomic, assign) BOOL firstLaunch;
 @property (nonatomic, assign) BOOL sessionResponseProcessed;
 
-- (_Nullable id)init;
-
 - (BOOL)isEnabled;
 - (BOOL)isDisabled;
 - (BOOL)isOffline;
@@ -49,7 +47,7 @@
 @property (nonatomic, strong) NSMutableArray *_Nullable preLaunchAdjustThirdPartySharingArray;
 @property (nonatomic, copy) NSNumber *_Nullable lastMeasurementConsentTracked;
 
-- (id _Nullable)init;
+- (nonnull id)init;
 
 @end
 
diff --git a/Adjust/ADJActivityHandler.m b/Adjust/ADJActivityHandler.m
index dc28062f7..7dc92a771 100644
--- a/Adjust/ADJActivityHandler.m
+++ b/Adjust/ADJActivityHandler.m
@@ -47,13 +47,6 @@
 
 @implementation ADJInternalState
 
-- (id)init {
-    self = [super init];
-    if (self == nil) return nil;
-
-    return self;
-}
-
 - (BOOL)isEnabled { return self.enabled; }
 - (BOOL)isDisabled { return !self.enabled; }
 - (BOOL)isOffline { return self.offline; }
@@ -72,10 +65,10 @@ @implementation ADJSavedPreLaunch
 
 - (id)init {
     self = [super init];
-    if (self == nil) return nil;
-
-    // online by default
-    self.offline = NO;
+    if (self) {
+        // online by default
+        self.offline = NO;
+    }
     return self;
 }
 
diff --git a/Adjust/ADJAdjustFactory.m b/Adjust/ADJAdjustFactory.m
index 4670a6245..800294201 100644
--- a/Adjust/ADJAdjustFactory.m
+++ b/Adjust/ADJAdjustFactory.m
@@ -242,6 +242,7 @@ + (void)teardown:(BOOL)deleteState {
     internalRequestTimeout = -1;
     packageHandlerBackoffStrategy = nil;
     sdkClickHandlerBackoffStrategy = nil;
+    installSessionBackoffStrategy = nil;
     internalTesting = NO;
     internalMaxDelayStart = -1;
     internalBaseUrl = nil;
diff --git a/Adjust/ADJPackageBuilder.m b/Adjust/ADJPackageBuilder.m
index 5a71e98e5..25c135eba 100644
--- a/Adjust/ADJPackageBuilder.m
+++ b/Adjust/ADJPackageBuilder.m
@@ -248,8 +248,8 @@ - (ADJActivityPackage *)buildSubscriptionPackage:(ADJSubscription *)subscription
     subscriptionPackage.parameters = parameters;
 
     if (isInDelay) {
-        subscriptionPackage.callbackParameters = subscriptionPackage.callbackParameters;
-        subscriptionPackage.partnerParameters = subscriptionPackage.partnerParameters;
+        subscriptionPackage.callbackParameters = subscription.callbackParameters;
+        subscriptionPackage.partnerParameters = subscription.partnerParameters;
     }
 
     [self signWithSigV2Plugin:subscriptionPackage];
@@ -264,9 +264,6 @@ + (void)parameters:(NSMutableDictionary *)parameters setDictionary:(NSDictionary
     if (dictionary.count == 0) {
         return;
     }
-    if (dictionary.count == 0) {
-        return;
-    }
 
     NSDictionary *convertedDictionary = [ADJUtil convertDictionaryValues:dictionary];
     [ADJPackageBuilder parameters:parameters setDictionaryJson:convertedDictionary forKey:key];
diff --git a/Adjust/ADJUtil.m b/Adjust/ADJUtil.m
index 26f7ed294..6258d2395 100644
--- a/Adjust/ADJUtil.m
+++ b/Adjust/ADJUtil.m
@@ -37,7 +37,7 @@
 static CTTelephonyNetworkInfo *networkInfo = nil;
 #endif
 
-static NSString * const kClientSdk                  = @"ios4.26.0";
+static NSString * const kClientSdk                  = @"ios4.26.1";
 static NSString * const kDeeplinkParam              = @"deep_link=";
 static NSString * const kSchemeDelimiter            = @"://";
 static NSString * const kDefaultScheme              = @"AdjustUniversalScheme";
diff --git a/Adjust/Adjust.h b/Adjust/Adjust.h
index 022e0c642..29461674f 100644
--- a/Adjust/Adjust.h
+++ b/Adjust/Adjust.h
@@ -2,7 +2,7 @@
 //  Adjust.h
 //  Adjust
 //
-//  V4.26.0
+//  V4.26.1
 //  Created by Christian Wellenbrock (wellle) on 23rd July 2013.
 //  Copyright © 2012-2017 Adjust GmbH. All rights reserved.
 //
diff --git a/AdjustBridge/AdjustBridgeRegister.m b/AdjustBridge/AdjustBridgeRegister.m
index 40a31cb7a..0be449c7d 100644
--- a/AdjustBridge/AdjustBridgeRegister.m
+++ b/AdjustBridge/AdjustBridgeRegister.m
@@ -246,7 +246,7 @@ + (NSString *)adjust_js {
                 if (this.sdkPrefix) {
                     return this.sdkPrefix;
                 } else {
-                    return 'web-bridge4.26.0';
+                    return 'web-bridge4.26.1';
                 }
             },
             setTestOptions: function(testOptions) {
diff --git a/AdjustTests/AdjustUnitTests/ADJPackageFields.m b/AdjustTests/AdjustUnitTests/ADJPackageFields.m
index d5f3a8627..2bacaee4e 100644
--- a/AdjustTests/AdjustUnitTests/ADJPackageFields.m
+++ b/AdjustTests/AdjustUnitTests/ADJPackageFields.m
@@ -16,7 +16,7 @@ - (id) init {
 
     // default values
     self.appToken = @"qwerty123456";
-    self.clientSdk = @"ios4.26.0";
+    self.clientSdk = @"ios4.26.1";
     self.suffix = @"";
     self.environment = @"sandbox";
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e20fe7f2a..8441139a4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+### Version 4.26.1 (5th February 2021)
+
+#### Fixed
+- Fixed nullability warnings.
+
+---
+
 ### Version 4.26.0 (3rd February 2021)
 #### Added
 - Added wrapper method `updateConversionValue:` method to `Adjust` API to allow updating SKAdNetwork conversion value via SDK API.
diff --git a/README.md b/README.md
index 832ce8ab7..80daa9179 100644
--- a/README.md
+++ b/README.md
@@ -83,13 +83,13 @@ We will describe the steps to integrate the Adjust SDK into your iOS project. We
 If you're using [CocoaPods][cocoapods], you can add the following line to your `Podfile` and continue from [this step](#sdk-integrate):
 
 ```ruby
-pod 'Adjust', '~> 4.26.0'
+pod 'Adjust', '~> 4.26.1'
 ```
 
 or:
 
 ```ruby
-pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.0'
+pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.1'
 ```
 
 ---
@@ -771,7 +771,8 @@ You can notify Adjust when a user disables, enables, and re-enables data sharing
 Call the following method to instruct the Adjust SDK to communicate the user's choice to disable data sharing to the Adjust backend:
 
 ```objc
-[Adjust disableThirdPartySharing];
+ADJThirdPartySharing *adjustThirdPartySharing = [[ADJThirdPartySharing alloc] initWithIsEnabledNumberBool:NO];
+[Adjust trackThirdPartySharing:adjustThirdPartySharing];
 ```
 
 Upon receiving this information, Adjust will block the sharing of that specific user's data to partners and the Adjust SDK will continue to work as usual.
diff --git a/VERSION b/VERSION
index 06edb3873..b02da5e24 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.26.0
+4.26.1
diff --git a/doc/chinese/README.md b/doc/chinese/README.md
index 0efa800ce..6c4d64b2d 100644
--- a/doc/chinese/README.md
+++ b/doc/chinese/README.md
@@ -76,13 +76,13 @@ Read this in other languages: [English][en-readme], [中文][zh-readme], [日本
 如果您正在使用[CocoaPods][cocoapods],您可以将以下代码行添加至 `Podfile`，然后继续进行[此步骤](#sdk-integrate):
 
 ```ruby
-pod 'Adjust', '~> 4.26.0'
+pod 'Adjust', '~> 4.26.1'
 ```
 
 或:
 
 ```ruby
-pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.0'
+pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.1'
 ```
 
 ---
diff --git a/doc/english/migrate.md b/doc/english/migrate.md
index ecdd48a58..b62a5448b 100644
--- a/doc/english/migrate.md
+++ b/doc/english/migrate.md
@@ -1,4 +1,4 @@
-## Migrate your Adjust SDK for iOS to v4.26.0 from v3.4.0
+## Migrate your Adjust SDK for iOS to v4.26.1 from v3.4.0
 
 ### Initial setup
 
diff --git a/doc/english/web_views.md b/doc/english/web_views.md
index 1920a33b4..314305c09 100644
--- a/doc/english/web_views.md
+++ b/doc/english/web_views.md
@@ -64,7 +64,7 @@ We will describe the steps to integrate the Adjust SDK into your iOS project. We
 If you're using [CocoaPods][cocoapods], you can add the following line to your `Podfile` and continue from [this step](#sdk-integrate):
 
 ```ruby
-pod 'Adjust/WebBridge', '~> 4.26.0'
+pod 'Adjust/WebBridge', '~> 4.26.1'
 ```
 
 ---
diff --git a/doc/japanese/README.md b/doc/japanese/README.md
index 1ec513f84..a96a4764a 100644
--- a/doc/japanese/README.md
+++ b/doc/japanese/README.md
@@ -25,13 +25,13 @@ adjust SDKをiOSプロジェクトに連携する手順を説明します。
 [こちらの手順](#sdk-integrate)に進んでください。
 
 ```ruby
-pod 'Adjust', '~> 4.26.0'
+pod 'Adjust', '~> 4.26.1'
 ```
 
 または
 
 ```ruby
-pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.0'
+pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.1'
 ```
 
 ---
diff --git a/doc/korean/README.md b/doc/korean/README.md
index 84eaeb912..95b82c339 100644
--- a/doc/korean/README.md
+++ b/doc/korean/README.md
@@ -76,13 +76,13 @@ iOS 개발용 Xcode를 사용한다는 가정하에 iOS 프로젝트에 Adjust S
 [CocoaPods][cocoapods]를 사용하는 경우, 다음 내용을 `Podfile`에 추가한 후 [해당 단계](#sdk-integrate)를 완료하세요.
 
 ```ruby
-pod 'Adjust', '~> 4.26.0'
+pod 'Adjust', '~> 4.26.1'
 ```
 
 또는:
 
 ```ruby
-pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.0'
+pod 'Adjust', :git => 'https://github.com/adjust/ios_sdk.git', :tag => 'v4.26.1'
 ```
 
 ---
diff --git a/doc/korean/web_views.md b/doc/korean/web_views.md
index 3570f6639..47f63becc 100644
--- a/doc/korean/web_views.md
+++ b/doc/korean/web_views.md
@@ -64,7 +64,7 @@ iOS 개발용 Xcode를 사용한다는 가정하에 iOS 프로젝트에 Adjust S
 [CocoaPods][cocoapods]를 사용하는 경우, 다음 내용을 'Podfile'에 추가한 후 [해당 단계](#sdk-integrate)를 완료하세요.
 
 ```ruby
-pod 'Adjust/WebBridge', '~> 4.26.0'
+pod 'Adjust/WebBridge', '~> 4.26.1'
 ```
 
 ---
diff --git a/doc/migrate.md b/doc/migrate.md
index ecdd48a58..b62a5448b 100644
--- a/doc/migrate.md
+++ b/doc/migrate.md
@@ -1,4 +1,4 @@
-## Migrate your Adjust SDK for iOS to v4.26.0 from v3.4.0
+## Migrate your Adjust SDK for iOS to v4.26.1 from v3.4.0
 
 ### Initial setup