diff --git a/codearchiver/core.py b/codearchiver/core.py
index 35a7d89..badcbcf 100644
--- a/codearchiver/core.py
+++ b/codearchiver/core.py
@@ -123,19 +123,23 @@ class Metadata(list[tuple[str, str]]):
 
 		permittedKeys = set(field.key for field in self._allFields)
 		unrecognisedKeys = keys - permittedKeys
-		if unrecognisedKeys:
-			raise MetadataValidationError(f'Unrecognised key(s): {", ".join(sorted(unrecognisedKeys))}')
 
 		requiredKeys = set(field.key for field in self._allFields if field.required)
 		missingRequiredKeys = requiredKeys - keys
-		if missingRequiredKeys:
-			raise MetadataValidationError(f'Missing required key(s): {", ".join(sorted(missingRequiredKeys))}')
 
 		repeatableKeys = set(field.key for field in self._allFields if field.repeatable)
 		repeatedKeys = set(key for key, count in keyCounts.items() if count > 1)
 		repeatedUnrepeatableKeys = repeatedKeys - repeatableKeys
+
+		errors = []
+		if unrecognisedKeys:
+			errors.append(f'unrecognised key(s): {", ".join(sorted(unrecognisedKeys))}')
+		if missingRequiredKeys:
+			errors.append(f'missing required key(s): {", ".join(sorted(missingRequiredKeys))}')
 		if repeatedUnrepeatableKeys:
-			raise MetadataValidationError(f'Repeated unrepeatable key(s): {", ".join(sorted(repeatedUnrepeatableKeys))}')
+			errors.append(f'repeated unrepeatable key(s): {", ".join(sorted(repeatedUnrepeatableKeys))}')
+		if errors:
+			raise MetadataValidationError('; '.join(errors))
 
 	def matches(self, criteria: list[tuple[str, typing.Union[str, tuple[str]]]]) -> bool:
 		'''