diff --git a/pageserver/src/http/routes.rs b/pageserver/src/http/routes.rs
index 6a10d4fb1c3e..ba38120bf1e6 100644
--- a/pageserver/src/http/routes.rs
+++ b/pageserver/src/http/routes.rs
@@ -589,6 +589,10 @@ async fn timeline_create_handler(
                 StatusCode::SERVICE_UNAVAILABLE,
                 HttpErrorBody::from_msg(e.to_string()),
             ),
+            Err(e @ tenant::CreateTimelineError::AncestorArchived) => json_response(
+                StatusCode::NOT_ACCEPTABLE,
+                HttpErrorBody::from_msg(e.to_string()),
+            ),
             Err(tenant::CreateTimelineError::ShuttingDown) => json_response(
                 StatusCode::SERVICE_UNAVAILABLE,
                 HttpErrorBody::from_msg("tenant shutting down".to_string()),
diff --git a/pageserver/src/tenant.rs b/pageserver/src/tenant.rs
index 53cbaea621eb..2aebf4f99932 100644
--- a/pageserver/src/tenant.rs
+++ b/pageserver/src/tenant.rs
@@ -563,6 +563,8 @@ pub enum CreateTimelineError {
     AncestorLsn(anyhow::Error),
     #[error("ancestor timeline is not active")]
     AncestorNotActive,
+    #[error("ancestor timeline is archived")]
+    AncestorArchived,
     #[error("tenant shutting down")]
     ShuttingDown,
     #[error(transparent)]
@@ -1698,6 +1700,11 @@ impl Tenant {
                     return Err(CreateTimelineError::AncestorNotActive);
                 }
 
+                if ancestor_timeline.is_archived() == Some(true) {
+                    info!("tried to branch archived timeline");
+                    return Err(CreateTimelineError::AncestorArchived);
+                }
+
                 if let Some(lsn) = ancestor_start_lsn.as_mut() {
                     *lsn = lsn.align();