diff --git a/src/main.rs b/src/main.rs
index e95f52a..bec2b28 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -41,59 +41,59 @@ mod profile;
 #[command(author, version, about, long_about = None)]
 #[command(propagate_version = true, arg_required_else_help(true))]
 struct Cli {
-    #[arg(
-        long = "input",
-        help = "Eingabedatei"
-    )]
+    #[arg(long = "input", help = "Eingabedatei")]
     input: String,
-    #[arg(
-        long = "profile",
-        help = "Profildatei (Optional)"
-    )]
+    #[arg(long = "profile", help = "Profildatei (Optional)")]
     profile: Option<String>,
-    #[arg(
-        long = "output",
-        help = "Ausgabedatei (Optional)"
-    )]
-    output: Option<String>
+    #[arg(long = "output", help = "Ausgabedatei (Optional)")]
+    output: Option<String>,
 }
 
 fn main() {
     let cli = Cli::parse();
 
-    let contents = fs::read_to_string(cli.input)
-        .expect("Should have been able to read the file");
+    let contents = fs::read_to_string(cli.input).expect("Should have been able to read the file");
 
-    let mut data: OnkostarEditor = from_str(contents.as_str()).unwrap();
+    if let Ok(mut data) = from_str::<OnkostarEditor>(contents.as_str()) {
+        data.apply_variant();
 
-    data.apply_variant();
+        let mut buf = String::new();
 
-    let mut buf = String::new();
+        let mut serializer = Serializer::new(&mut buf);
+        serializer.indent(' ', 2);
 
-    let mut serializer = Serializer::new(&mut buf);
-    serializer.indent(' ', 2);
+        data.serialize(serializer).expect("Generated XML");
 
-    data.serialize(serializer).expect("Generated XML");
+        let output = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+            .to_string()
+            .add(
+                buf
+                    // Replace &apos; and &quot; as used in original file
+                    .replace("&apos;", "'")
+                    .replace("&quot;", "\"")
+                    .as_str(),
+            );
 
-    let output = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n".to_string()
-        .add(buf
-            // Replace &apos; and &quot; as used in original file
-            .replace("&apos;", "'")
-            .replace("&quot;", "\"")
-            .as_str());
-
-    match cli.output {
-        Some(filename) => {
-            let mut file = OpenOptions::new()
-                .read(false)
-                .write(true)
-                .create(true)
-                .truncate(true)
-                .open(filename).unwrap();
-            file.write_all(output.as_bytes()).expect("Should have written output file");
-        },
-        None => {
-            println!("{}", output)
+        match cli.output {
+            Some(filename) => {
+                let mut file = OpenOptions::new()
+                    .read(false)
+                    .write(true)
+                    .create(true)
+                    .truncate(true)
+                    .open(filename)
+                    .unwrap();
+                file.write_all(output.as_bytes())
+                    .expect("Should have written output file");
+            }
+            None => {
+                println!("{}", output)
+            }
         }
+    } else {
+        eprintln!("Kann Eingabedatei nicht lesen!");
+        eprintln!(
+            "Die Datei ist entweder keine OSC-Datei, fehlerhaft oder enthält zusätzliche Inhalte."
+        );
     }
 }
diff --git a/src/model/data_catalogue.rs b/src/model/data_catalogue.rs
index ffe432d..eba84c3 100644
--- a/src/model/data_catalogue.rs
+++ b/src/model/data_catalogue.rs
@@ -27,6 +27,7 @@ use serde::{Deserialize, Serialize};
 use crate::model::Ordner;
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataCatalogue {
     #[serde(rename = "Name")]
     name: String,
@@ -55,12 +56,14 @@ pub struct DataCatalogue {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Entries {
     #[serde(rename = "Entry")]
     entry: Vec<Entry>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Entry {
     #[serde(rename = "PropertyCatalogue")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -122,12 +125,14 @@ pub struct Entry {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Use {
     #[serde(rename = "ProgramModule", default)]
     program_module: Vec<ProgramModule>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct ProgramModule {
     #[serde(rename = "@program")]
     program: String,
diff --git a/src/model/data_form.rs b/src/model/data_form.rs
index 037fa8d..ce0b1d3 100644
--- a/src/model/data_form.rs
+++ b/src/model/data_form.rs
@@ -28,6 +28,7 @@ use crate::model::Ordner;
 use crate::model::{Ansichten, Entries, Filter, MenuCategory, PlausibilityRules, Script};
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataForm {
     #[serde(rename = "DataCatalogues")]
     data_catalogues: DataCatalogues,
@@ -162,12 +163,14 @@ impl DataForm {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataCatalogues {
     #[serde(rename = "DataCatalogue")]
     data_catalogue: Vec<String>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Entry {
     #[serde(rename = "@parentId")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -354,6 +357,7 @@ pub struct Entry {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataFormEntries {
     #[serde(rename = "EntryName")]
     entry_name: Option<Vec<String>>,
diff --git a/src/model/mod.rs b/src/model/mod.rs
index 2b4aa89..8353f64 100644
--- a/src/model/mod.rs
+++ b/src/model/mod.rs
@@ -31,6 +31,7 @@ pub mod property_catalogue;
 pub mod unterformular;
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Script {
     #[serde(rename = "Code")]
     code: String,
@@ -39,6 +40,7 @@ pub struct Script {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct PlausibilityRule<T> {
     #[serde(rename = "Type")]
     type_: String,
@@ -69,12 +71,14 @@ pub struct PlausibilityRule<T> {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Entries<T> {
     #[serde(rename = "Entry")]
     entry: Vec<T>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Ansicht {
     #[serde(rename = "Name")]
     name: String,
@@ -101,12 +105,14 @@ pub struct Ansicht {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Ansichten {
     #[serde(rename = "Ansicht", default)]
     program_module: Vec<Ansicht>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct MenuCategory {
     #[serde(rename = "name")]
     name: String,
@@ -117,6 +123,7 @@ pub struct MenuCategory {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Filter {
     #[serde(rename = "Condition")]
     condition: String,
@@ -128,6 +135,7 @@ pub struct Filter {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct RefEntries {
     #[serde(rename = "RefEntry")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -135,6 +143,7 @@ pub struct RefEntries {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct PlausibilityRules<T> {
     #[serde(rename = "PlausibilityRule")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -142,12 +151,14 @@ pub struct PlausibilityRules<T> {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Bibliothek {
     #[serde(rename = "Name")]
     name: String,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Ordner {
     #[serde(rename = "Bibliothek")]
     bibliothek: Bibliothek,
diff --git a/src/model/onkostar_editor.rs b/src/model/onkostar_editor.rs
index 2102741..2d2b51e 100644
--- a/src/model/onkostar_editor.rs
+++ b/src/model/onkostar_editor.rs
@@ -30,6 +30,7 @@ use crate::model::property_catalogue::PropertyCatalogue;
 use crate::model::unterformular::Unterformular;
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct OnkostarEditor {
     #[serde(rename = "InfoXML")]
     info_xml: InfoXML,
@@ -49,6 +50,7 @@ impl OnkostarEditor {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct InfoXML {
     #[serde(rename = "DatumXML")]
     datum_xml: String,
@@ -59,6 +61,7 @@ pub struct InfoXML {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 struct Editor {
     #[serde(rename = "PropertyCatalogue")]
     property_catalogue: Vec<PropertyCatalogue>,
@@ -71,6 +74,7 @@ struct Editor {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Bibliothek {
     #[serde(rename = "Name")]
     name: String,
diff --git a/src/model/property_catalogue.rs b/src/model/property_catalogue.rs
index db1c3b7..8507ea5 100644
--- a/src/model/property_catalogue.rs
+++ b/src/model/property_catalogue.rs
@@ -27,6 +27,7 @@ use serde::{Deserialize, Serialize};
 use crate::model::Ordner;
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct PropertyCatalogue {
     #[serde(rename = "Name")]
     name: String,
@@ -52,6 +53,7 @@ pub struct PropertyCatalogue {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Versions {
     #[serde(rename = "Version")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -59,6 +61,7 @@ pub struct Versions {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Version {
     #[serde(rename = "VersionNumber")]
     version_number: u16,
@@ -86,12 +89,14 @@ pub struct Version {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct VersionEntries {
     #[serde(rename = "Entry", default)]
     content: Vec<VersionEntry>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct VersionEntry {
     #[serde(rename = "Code")]
     code: String,
@@ -110,12 +115,14 @@ pub struct VersionEntry {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Categories {
     #[serde(rename = "Category", default)]
     content: Vec<Category>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Category {
     #[serde(rename = "Name")]
     name: String,
@@ -132,12 +139,14 @@ pub struct Category {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct CategoryEntries {
     #[serde(rename = "CategoryEntry", default)]
     content: Vec<CategoryEntry>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct CategoryEntry {
     #[serde(rename = "Code")]
     code: String,
@@ -156,6 +165,7 @@ pub struct CategoryEntry {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Abbildung {
     #[serde(rename = "ZielMKVersionOid")]
     ziel_mk_version_oid: String,
@@ -164,6 +174,7 @@ pub struct Abbildung {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct AbbildungEintrag {
     #[serde(rename = "Entry-from")]
     entry_from: AbbildungEntry,
@@ -172,6 +183,7 @@ pub struct AbbildungEintrag {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct AbbildungEntry {
     #[serde(rename = "Code")]
     code: String,
diff --git a/src/model/unterformular.rs b/src/model/unterformular.rs
index 261aa9a..66d5eb9 100644
--- a/src/model/unterformular.rs
+++ b/src/model/unterformular.rs
@@ -28,6 +28,7 @@ use crate::model::Ordner;
 use crate::model::{Ansichten, Entries, Filter, MenuCategory, PlausibilityRules, Script};
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Unterformular {
     #[serde(rename = "DataCatalogues")]
     data_catalogues: DataCatalogues,
@@ -170,12 +171,14 @@ impl Unterformular {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataCatalogues {
     #[serde(rename = "DataCatalogue")]
     data_catalogue: Vec<String>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct Entry {
     #[serde(rename = "@parentId")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -363,6 +366,7 @@ pub struct Entry {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
 pub struct DataFormEntries {
     #[serde(rename = "EntryName")]
     #[serde(skip_serializing_if = "Option::is_none")]