diff --git a/tuf/api/metadata.py b/tuf/api/metadata.py
index dadc51a6..ee37df91 100644
--- a/tuf/api/metadata.py
+++ b/tuf/api/metadata.py
@@ -384,7 +384,7 @@ def sign(
         try:
             signature = signer.sign(bytes_data)
         except Exception as e:
-            raise UnsignedMetadataError("Problem signing the metadata") from e
+            raise UnsignedMetadataError(f"Failed to sign: {e}") from e
 
         if not append:
             self.signatures.clear()