diff --git a/crates/uv-workspace/src/dependency_groups.rs b/crates/uv-workspace/src/dependency_groups.rs
index edb4ef88e..ad3e9b4b2 100644
--- a/crates/uv-workspace/src/dependency_groups.rs
+++ b/crates/uv-workspace/src/dependency_groups.rs
@@ -3,7 +3,7 @@ use std::collections::BTreeMap;
 use std::str::FromStr;
 
 use thiserror::Error;
-use tracing::warn;
+use tracing::error;
 
 use uv_normalize::{GroupName, DEV_DEPENDENCIES};
 use uv_pep508::Pep508Error;
@@ -74,9 +74,10 @@ impl FlatDependencyGroups {
                             .extend(resolved.get(include_group).into_iter().flatten().cloned());
                     }
                     DependencyGroupSpecifier::Object(map) => {
-                        warn!(
-                            "Ignoring Dependency Object Specifier referenced by `{name}`: {map:?}"
-                        );
+                        return Err(DependencyGroupError::DependencyObjectSpecifierNotSupported(
+                            name.clone(),
+                            map.clone(),
+                        ));
                     }
                 }
             }
@@ -154,6 +155,8 @@ pub enum DependencyGroupError {
     DevGroupInclude(GroupName),
     #[error("Detected a cycle in `dependency-groups`: {0}")]
     DependencyGroupCycle(Cycle),
+    #[error("Group `{0}` contains an unknown dependency object specifier: {1:?}")]
+    DependencyObjectSpecifierNotSupported(GroupName, BTreeMap<String, String>),
 }
 
 impl DependencyGroupError {
diff --git a/crates/uv/tests/it/lock.rs b/crates/uv/tests/it/lock.rs
index 2eb497294..5c7a1202b 100644
--- a/crates/uv/tests/it/lock.rs
+++ b/crates/uv/tests/it/lock.rs
@@ -20833,14 +20833,15 @@ fn lock_group_invalid_entry_table() -> Result<()> {
         "#,
     )?;
 
-    uv_snapshot!(context.filters(), context.lock(), @r###"
-    success: true
-    exit_code: 0
+    uv_snapshot!(context.filters(), context.lock(), @r#"
+    success: false
+    exit_code: 1
     ----- stdout -----
 
     ----- stderr -----
-    Resolved 2 packages in [TIME]
-    "###);
+      × Failed to build `project @ file://[TEMP_DIR]/`
+      ╰─▶ Group `foo` contains an unknown dependency object specifier: {"bar": "unknown"}
+    "#);
 
     Ok(())
 }