diff --git a/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/converter/CallbackAuthenticationConverter.java b/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/converter/CallbackAuthenticationConverter.java
index ac888aab9..59078a20e 100644
--- a/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/converter/CallbackAuthenticationConverter.java
+++ b/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/converter/CallbackAuthenticationConverter.java
@@ -26,6 +26,7 @@
 import org.springframework.stereotype.Component;
 
 import java.io.IOException;
+import java.util.Objects;
 
 /**
  * Converter for callback request authentication.
@@ -48,17 +49,13 @@ public CallbackAuthenticationConverter(ObjectMapper objectMapper) {
     }
 
     @Override
-    public String convertToDatabaseColumn(CallbackUrlAuthentication authentication) {
+    public String convertToDatabaseColumn(final CallbackUrlAuthentication authentication) {
         try {
-            if (authentication == null) {
-                authentication = new CallbackUrlAuthentication();
-            }
-            return objectMapper.writeValueAsString(authentication);
+            return objectMapper.writeValueAsString(Objects.requireNonNullElse(authentication, new CallbackUrlAuthentication()));
         } catch (JsonProcessingException ex) {
             logger.error("Unable to serialize JSON payload", ex);
             return null;
         }
-
     }
 
     @Override
diff --git a/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/service/encryption/EncryptionService.java b/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/service/encryption/EncryptionService.java
index 0da9b5ccb..91dd8771d 100644
--- a/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/service/encryption/EncryptionService.java
+++ b/powerauth-java-server/src/main/java/io/getlime/security/powerauth/app/server/service/encryption/EncryptionService.java
@@ -151,6 +151,10 @@ public byte[] decrypt(final byte[] data, final EncryptionMode encryptionMode, fi
      * @throws GenericServiceException Thrown when encryption fails.
      */
     public EncryptableString encrypt(final String data, final Supplier<List<String>> encryptionKeyProvider) throws GenericServiceException {
+        if (data == null) {
+            throw new GenericServiceException(ServiceError.ENCRYPTION_FAILED, "Data must not be null");
+        }
+
         final byte[] dataBytes = data.getBytes(StandardCharsets.UTF_8);
         final EncryptableData result = encrypt(dataBytes, encryptionKeyProvider);
         return new EncryptableString(result.encryptionMode(), convert(result));
@@ -166,6 +170,10 @@ public EncryptableString encrypt(final String data, final Supplier<List<String>>
      * @throws GenericServiceException Thrown when encryption fails.
      */
     public EncryptableData encrypt(final byte[] data, final Supplier<List<String>> encryptionKeyProvider) throws GenericServiceException {
+        if (data == null) {
+            throw new GenericServiceException(ServiceError.ENCRYPTION_FAILED, "Data must not be null");
+        }
+
         final String masterDbEncryptionKeyBase64 = powerAuthServiceConfiguration.getMasterDbEncryptionKey();
 
         // In case master DB encryption key does not exist, do not encrypt the value