diff --git a/openraft/src/error.rs b/openraft/src/error.rs
index 628b421e9..315bdd2e3 100644
--- a/openraft/src/error.rs
+++ b/openraft/src/error.rs
@@ -136,9 +136,6 @@ pub enum AddLearnerError<NID: NodeId> {
     #[error(transparent)]
     ForwardToLeader(#[from] ForwardToLeader<NID>),
 
-    #[error("node {0} is already a learner")]
-    Exists(NID),
-
     #[error(transparent)]
     MissingNodeInfo(#[from] MissingNodeInfo<NID>),