diff --git a/pageserver/src/tenant/timeline.rs b/pageserver/src/tenant/timeline.rs
index e9892a0002..dc31cd5fb2 100644
--- a/pageserver/src/tenant/timeline.rs
+++ b/pageserver/src/tenant/timeline.rs
@@ -590,8 +590,8 @@ impl From<GetVectoredError> for PageReconstructError {
     fn from(e: GetVectoredError) -> Self {
         match e {
             GetVectoredError::Cancelled => PageReconstructError::Cancelled,
+            GetVectoredError::InvalidLsn(_) => PageReconstructError::Other(anyhow!("Invalid LSN")),
             err @ GetVectoredError::Oversized(_) => PageReconstructError::Other(err.into()),
-            err @ GetVectoredError::InvalidLsn(_) => PageReconstructError::Other(err.into()),
             err @ GetVectoredError::MissingKey(_) => PageReconstructError::Other(err.into()),
             err @ GetVectoredError::GetReadyAncestorError(_) => PageReconstructError::from(err),
             GetVectoredError::Other(err) => PageReconstructError::Other(err),
@@ -707,6 +707,15 @@ impl Timeline {
         lsn: Lsn,
         ctx: &RequestContext,
     ) -> Result<Bytes, PageReconstructError> {
+        if !lsn.is_valid() {
+            return Err(PageReconstructError::Other(anyhow::anyhow!("Invalid LSN")));
+        }
+
+        // This check is debug-only because of the cost of hashing, and because it's a double-check: we
+        // already checked the key against the shard_identity when looking up the Timeline from
+        // page_service.
+        debug_assert!(!self.shard_identity.is_key_disposable(&key));
+
         self.timeline_get_throttle.throttle(ctx, 1).await;
 
         // Check the page cache. We will get back the most recent page with lsn <= `lsn`.
@@ -798,15 +807,6 @@ impl Timeline {
         mut reconstruct_state: ValueReconstructState,
         ctx: &RequestContext,
     ) -> Result<Bytes, PageReconstructError> {
-        if !lsn.is_valid() {
-            return Err(PageReconstructError::Other(anyhow::anyhow!("Invalid LSN")));
-        }
-
-        // This check is debug-only because of the cost of hashing, and because it's a double-check: we
-        // already checked the key against the shard_identity when looking up the Timeline from
-        // page_service.
-        debug_assert!(!self.shard_identity.is_key_disposable(&key));
-
         // XXX: structured stats collection for layer eviction here.
         trace!(
             "get page request for {}@{} from task kind {:?}",