diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/AccessTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/AccessTypeConverter.java
index 80aa0686280085f2710c419b3d150d927588eb9e..e8ee655c8b054df2592dc0208b2b02baeb8f4327 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/AccessTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/AccessTypeConverter.java
@@ -9,12 +9,18 @@ public class AccessTypeConverter implements AttributeConverter<AccessType, Strin
 
     @Override
     public String convertToDatabaseColumn(AccessType accessType) {
+        if (accessType == null) {
+            return null;
+        }
         return accessType.name()
                 .toLowerCase();
     }
 
     @Override
     public AccessType convertToEntityAttribute(String accessType) {
+        if (accessType == null) {
+            return null;
+        }
         return AccessType.valueOf(accessType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/BannerMessageTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/BannerMessageTypeConverter.java
new file mode 100644
index 0000000000000000000000000000000000000000..24143a7453a074456431b8c2ccc89c00ef1b6f8e
--- /dev/null
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/BannerMessageTypeConverter.java
@@ -0,0 +1,26 @@
+package at.tuwien.converters;
+
+import at.tuwien.entities.maintenance.BannerMessageType;
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Converter;
+
+@Converter
+public class BannerMessageTypeConverter implements AttributeConverter<BannerMessageType, String> {
+
+    @Override
+    public String convertToDatabaseColumn(BannerMessageType bannerMessageType) {
+        if (bannerMessageType == null) {
+            return null;
+        }
+        return bannerMessageType.name()
+                .toLowerCase();
+    }
+
+    @Override
+    public BannerMessageType convertToEntityAttribute(String bannerMessageType) {
+        if (bannerMessageType == null) {
+            return null;
+        }
+        return BannerMessageType.valueOf(bannerMessageType.toUpperCase());
+    }
+}
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierAffiliationIdentifierSchemeTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierAffiliationIdentifierSchemeTypeConverter.java
index ba8a0a43fb6c3fe5a99a7704cd3f3e8620fff0c5..7afc5975b109c6095f2d7017618d0ac9541bb780 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierAffiliationIdentifierSchemeTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierAffiliationIdentifierSchemeTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierAffiliationIdentifierSchemeTypeConverter implements AttributeConverter<AffiliationIdentifierSchemeType, String> {
 
     @Override
-    public String convertToDatabaseColumn(AffiliationIdentifierSchemeType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(AffiliationIdentifierSchemeType affiliationIdentifierSchemeType) {
+        if (affiliationIdentifierSchemeType == null) {
+            return null;
+        }
+        return affiliationIdentifierSchemeType.name()
                 .toLowerCase();
     }
 
     @Override
-    public AffiliationIdentifierSchemeType convertToEntityAttribute(String columnType) {
-        return AffiliationIdentifierSchemeType.valueOf(columnType.toUpperCase());
+    public AffiliationIdentifierSchemeType convertToEntityAttribute(String affiliationIdentifierSchemeType) {
+        if (affiliationIdentifierSchemeType == null) {
+            return null;
+        }
+        return AffiliationIdentifierSchemeType.valueOf(affiliationIdentifierSchemeType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierDescriptionTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierDescriptionTypeConverter.java
index 767733862d7423e2c7747200c967b4315f28db62..d426126a569694ca35aea34be1395765793b2e0b 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierDescriptionTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierDescriptionTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierDescriptionTypeConverter implements AttributeConverter<DescriptionType, String> {
 
     @Override
-    public String convertToDatabaseColumn(DescriptionType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(DescriptionType descriptionType) {
+        if (descriptionType == null) {
+            return null;
+        }
+        return descriptionType.name()
                 .toLowerCase();
     }
 
     @Override
-    public DescriptionType convertToEntityAttribute(String columnType) {
-        return DescriptionType.valueOf(columnType.toUpperCase());
+    public DescriptionType convertToEntityAttribute(String descriptionType) {
+        if (descriptionType == null) {
+            return null;
+        }
+        return DescriptionType.valueOf(descriptionType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierFunderTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierFunderTypeConverter.java
index 48d4200b2078df0e1d837338107a8469aedd42ce..c7214475510ad756bb851ddec31eded77f87f8cd 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierFunderTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierFunderTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierFunderTypeConverter implements AttributeConverter<IdentifierFunderType, String> {
 
     @Override
-    public String convertToDatabaseColumn(IdentifierFunderType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(IdentifierFunderType identifierFunderType) {
+        if (identifierFunderType == null) {
+            return null;
+        }
+        return identifierFunderType.name()
                 .toLowerCase();
     }
 
     @Override
-    public IdentifierFunderType convertToEntityAttribute(String columnType) {
-        return IdentifierFunderType.valueOf(columnType.toUpperCase());
+    public IdentifierFunderType convertToEntityAttribute(String identifierFunderType) {
+        if (identifierFunderType == null) {
+            return null;
+        }
+        return IdentifierFunderType.valueOf(identifierFunderType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierIdentifierTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierIdentifierTypeConverter.java
index f44a393663facd7a31a61fb301a6b5c716e32bd6..e78553256b0c825e3235f6a204047c40704eb6c3 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierIdentifierTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierIdentifierTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierIdentifierTypeConverter implements AttributeConverter<IdentifierType, String> {
 
     @Override
-    public String convertToDatabaseColumn(IdentifierType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(IdentifierType identifierType) {
+        if (identifierType == null) {
+            return null;
+        }
+        return identifierType.name()
                 .toLowerCase();
     }
 
     @Override
-    public IdentifierType convertToEntityAttribute(String columnType) {
-        return IdentifierType.valueOf(columnType.toUpperCase());
+    public IdentifierType convertToEntityAttribute(String identifierType) {
+        if (identifierType == null) {
+            return null;
+        }
+        return IdentifierType.valueOf(identifierType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameIdentifierSchemeTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameIdentifierSchemeTypeConverter.java
index 365177d783b118983a2e18c7c7078c5b7735787c..e5b74326aab5c6cedd74427f8cb2b75818607ac8 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameIdentifierSchemeTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameIdentifierSchemeTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierNameIdentifierSchemeTypeConverter implements AttributeConverter<NameIdentifierSchemeType, String> {
 
     @Override
-    public String convertToDatabaseColumn(NameIdentifierSchemeType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(NameIdentifierSchemeType nameIdentifierSchemeType) {
+        if (nameIdentifierSchemeType == null) {
+            return null;
+        }
+        return nameIdentifierSchemeType.name()
                 .toLowerCase();
     }
 
     @Override
-    public NameIdentifierSchemeType convertToEntityAttribute(String columnType) {
-        return NameIdentifierSchemeType.valueOf(columnType.toUpperCase());
+    public NameIdentifierSchemeType convertToEntityAttribute(String nameIdentifierSchemeType) {
+        if (nameIdentifierSchemeType == null) {
+            return null;
+        }
+        return NameIdentifierSchemeType.valueOf(nameIdentifierSchemeType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameTypeConverter.java
index 8eb9fc7afe423a232610d8272e2c0b5b9e7757b8..c43f26af311c48ff25099e78586ed4aa28b14b5f 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierNameTypeConverter.java
@@ -9,13 +9,19 @@ import jakarta.persistence.Converter;
 public class IdentifierNameTypeConverter implements AttributeConverter<NameType, String> {
 
     @Override
-    public String convertToDatabaseColumn(NameType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(NameType nameType) {
+        if (nameType == null) {
+            return null;
+        }
+        return nameType.name()
                 .toLowerCase();
     }
 
     @Override
-    public NameType convertToEntityAttribute(String columnType) {
-        return NameType.valueOf(columnType.toUpperCase());
+    public NameType convertToEntityAttribute(String nameType) {
+        if (nameType == null) {
+            return null;
+        }
+        return NameType.valueOf(nameType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierRelatedTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierRelatedTypeConverter.java
index 1fef4cb8b26aeea62c0e3a65a674f79175680f1d..93309f8049869febbcb221b16b3f3ccb8d4add54 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierRelatedTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierRelatedTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierRelatedTypeConverter implements AttributeConverter<RelatedType, String> {
 
     @Override
-    public String convertToDatabaseColumn(RelatedType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(RelatedType relatedType) {
+        if (relatedType == null) {
+            return null;
+        }
+        return relatedType.name()
                 .toLowerCase();
     }
 
     @Override
-    public RelatedType convertToEntityAttribute(String columnType) {
-        return RelatedType.valueOf(columnType.toUpperCase());
+    public RelatedType convertToEntityAttribute(String relatedType) {
+        if (relatedType == null) {
+            return null;
+        }
+        return RelatedType.valueOf(relatedType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierVisibilityTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierVisibilityTypeConverter.java
index 756f73b84768b882b1f1b23caaf8c201f0e4bbc6..f6e63297687b3d40b7a33117678697cd4099858f 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierVisibilityTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/IdentifierVisibilityTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class IdentifierVisibilityTypeConverter implements AttributeConverter<VisibilityType, String> {
 
     @Override
-    public String convertToDatabaseColumn(VisibilityType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(VisibilityType visibilityType) {
+        if (visibilityType == null) {
+            return null;
+        }
+        return visibilityType.name()
                 .toLowerCase();
     }
 
     @Override
-    public VisibilityType convertToEntityAttribute(String columnType) {
-        return VisibilityType.valueOf(columnType.toUpperCase());
+    public VisibilityType convertToEntityAttribute(String visibilityType) {
+        if (visibilityType == null) {
+            return null;
+        }
+        return VisibilityType.valueOf(visibilityType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/LanguageTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/LanguageTypeConverter.java
index 5d132af64d375a1cbc62fa11d70eb4444dfb3377..dad10800f45698b9547f22ec744025c9d0687a99 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/LanguageTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/LanguageTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class LanguageTypeConverter implements AttributeConverter<LanguageType, String> {
 
     @Override
-    public String convertToDatabaseColumn(LanguageType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(LanguageType languageType) {
+        if (languageType == null) {
+            return null;
+        }
+        return languageType.name()
                 .toLowerCase();
     }
 
     @Override
-    public LanguageType convertToEntityAttribute(String columnType) {
-        return LanguageType.valueOf(columnType.toUpperCase());
+    public LanguageType convertToEntityAttribute(String languageType) {
+        if (languageType == null) {
+            return null;
+        }
+        return LanguageType.valueOf(languageType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/TableColumnTypeConverter.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/TableColumnTypeConverter.java
index 7be348e8fd754fc5a10f31217b0af10872a4d094..f057f7233233fa61ce880451666443c9c6a4a522 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/TableColumnTypeConverter.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/converters/TableColumnTypeConverter.java
@@ -8,13 +8,19 @@ import jakarta.persistence.Converter;
 public class TableColumnTypeConverter implements AttributeConverter<TableColumnType, String> {
 
     @Override
-    public String convertToDatabaseColumn(TableColumnType columnType) {
-        return columnType.name()
+    public String convertToDatabaseColumn(TableColumnType tableColumnType) {
+        if (tableColumnType == null) {
+            return null;
+        }
+        return tableColumnType.name()
                 .toLowerCase();
     }
 
     @Override
-    public TableColumnType convertToEntityAttribute(String columnType) {
-        return TableColumnType.valueOf(columnType.toUpperCase());
+    public TableColumnType convertToEntityAttribute(String tableColumnType) {
+        if (tableColumnType == null) {
+            return null;
+        }
+        return TableColumnType.valueOf(tableColumnType.toUpperCase());
     }
 }
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessage.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessage.java
index befcec9c73b668e93fc81e1aee53fd6558988aa1..70c5abd8d81d4d0438ebb8f903b9dcffe06f6c7f 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessage.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessage.java
@@ -1,5 +1,6 @@
 package at.tuwien.entities.maintenance;
 
+import at.tuwien.converters.BannerMessageTypeConverter;
 import jakarta.persistence.*;
 import lombok.*;
 import org.hibernate.annotations.GenericGenerator;
@@ -27,8 +28,8 @@ public class BannerMessage {
     @Column(updatable = false, nullable = false)
     private Long id;
 
-    @Enumerated(EnumType.STRING)
     @Column(nullable = false, columnDefinition = "enum('error', 'warning', 'info')")
+    @Convert(converter = BannerMessageTypeConverter.class)
     private BannerMessageType type;
 
     @Column(nullable = false)
diff --git a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessageType.java b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessageType.java
index 8d17965f482754e5c9e9aed8e6c9e9c82b6ab650..fbfdab9711e4f25d556bbf584fc3cd1da3b49cbb 100644
--- a/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessageType.java
+++ b/dbrepo-metadata-service/entities/src/main/java/at/tuwien/entities/maintenance/BannerMessageType.java
@@ -1,13 +1,24 @@
-
 package at.tuwien.entities.maintenance;
 
 import lombok.Getter;
-import lombok.ToString;
 
 @Getter
-@ToString
 public enum BannerMessageType {
-    WARNING,
-    ERROR,
-    INFO;
+
+    WARNING("warning"),
+
+    ERROR("error"),
+
+    INFO("info");
+
+    private String name;
+
+    BannerMessageType(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return this.name;
+    }
 }
\ No newline at end of file