diff --git a/Source/ConfigCat/Private/ConfigCatSubsystem.cpp b/Source/ConfigCat/Private/ConfigCatSubsystem.cpp
index 87de149..0d6224b 100644
--- a/Source/ConfigCat/Private/ConfigCatSubsystem.cpp
+++ b/Source/ConfigCat/Private/ConfigCatSubsystem.cpp
@@ -283,12 +283,18 @@ bool UConfigCatSubsystem::IsOffline() const
 
 void UConfigCatSubsystem::Initialize(FSubsystemCollectionBase& Collection)
 {
-	const FString CppSdkVersion = UTF8_TO_TCHAR(configcat::version);
-	UE_LOG(LogConfigCat, Display, TEXT("ConfigCat Subsystem initializing cpp-sdk - %s"), *CppSdkVersion);
-
 	const UConfigCatSettings* ConfigCatSettings = GetDefault<UConfigCatSettings>();
+	if(!ConfigCatSettings || ConfigCatSettings->SdkKey.IsEmpty())
+	{
+		UE_LOG(LogConfigCat, Warning, TEXT("Empty SdkKey detected. Please set your SdkKey in the Project Settings."));
+		return;
+	}
+
 	const std::string& SdkKey = TCHAR_TO_UTF8(*ConfigCatSettings->SdkKey);
 
+	const FString CppSdkVersion = UTF8_TO_TCHAR(configcat::version);
+	UE_LOG(LogConfigCat, Display, TEXT("ConfigCat Subsystem initializing cpp-sdk - %s"), *CppSdkVersion);
+
 	ConfigCatOptions Options;
 	Options.baseUrl = TCHAR_TO_UTF8(*ConfigCatSettings->BaseUrl);
 	Options.dataGovernance = ConfigCatSettings->DataGovernance == EDataGovernance::Global ? Global : EuOnly;