diff --git a/src/cli/commands/explain.rs b/src/cli/commands/explain.rs
index 04172f2..3293bdb 100644
--- a/src/cli/commands/explain.rs
+++ b/src/cli/commands/explain.rs
@@ -823,7 +823,8 @@ fn fetch_related_entities(
         vec![]
     };
 
-    // Outgoing references (excluding closes, shown above)
+    // Outgoing references (excluding closes, shown above).
+    // Filter out unresolved refs (NULL target_entity_iid) to avoid rusqlite type errors.
     let mut out_stmt = conn.prepare(
         "SELECT er.target_entity_type, er.target_entity_iid, er.reference_type, \
                 COALESCE(i.title, mr.title) as title \
@@ -831,7 +832,8 @@ fn fetch_related_entities(
          LEFT JOIN issues i ON er.target_entity_type = 'issue' AND i.id = er.target_entity_id \
          LEFT JOIN merge_requests mr ON er.target_entity_type = 'merge_request' AND mr.id = er.target_entity_id \
          WHERE er.source_entity_type = ?1 AND er.source_entity_id = ?2 \
-           AND er.reference_type != 'closes'",
+           AND er.reference_type != 'closes' \
+           AND er.target_entity_iid IS NOT NULL",
     )?;
 
     let outgoing: Vec<RelatedEntityInfo> = out_stmt
@@ -845,7 +847,8 @@ fn fetch_related_entities(
         })?
         .collect::<std::result::Result<Vec<_>, _>>()?;
 
-    // Incoming references (excluding closes)
+    // Incoming references (excluding closes).
+    // COALESCE(i.iid, mr.iid) can be NULL if the source entity was deleted; filter those out.
     let mut in_stmt = conn.prepare(
         "SELECT er.source_entity_type, COALESCE(i.iid, mr.iid) as iid, er.reference_type, \
                 COALESCE(i.title, mr.title) as title \
@@ -853,7 +856,8 @@ fn fetch_related_entities(
          LEFT JOIN issues i ON er.source_entity_type = 'issue' AND i.id = er.source_entity_id \
          LEFT JOIN merge_requests mr ON er.source_entity_type = 'merge_request' AND mr.id = er.source_entity_id \
          WHERE er.target_entity_type = ?1 AND er.target_entity_id = ?2 \
-           AND er.reference_type != 'closes'",
+           AND er.reference_type != 'closes' \
+           AND COALESCE(i.iid, mr.iid) IS NOT NULL",
     )?;
 
     let incoming: Vec<RelatedEntityInfo> = in_stmt
@@ -1924,6 +1928,29 @@ mod tests {
         assert_eq!(related.closing_mrs[0].state, "merged");
     }
 
+    #[test]
+    fn test_explain_related_skips_unresolved_refs() {
+        let (conn, project_id) = setup_explain_db();
+        let issue_id = insert_test_issue(&conn, project_id, 65, Some("desc"));
+
+        // Insert an unresolved cross-project reference (NULL target_entity_iid)
+        conn.execute(
+            "INSERT INTO entity_references (project_id, source_entity_type, source_entity_id, \
+             target_entity_type, target_entity_id, target_entity_iid, reference_type, \
+             source_method, created_at) \
+             VALUES (?, 'issue', ?, 'issue', NULL, NULL, 'mentioned', 'note_parse', 1000000)",
+            rusqlite::params![project_id, issue_id],
+        )
+        .unwrap();
+
+        // Should NOT crash — unresolved refs are filtered out
+        let related = fetch_related_entities(&conn, "issues", issue_id).unwrap();
+        assert!(
+            related.related_issues.is_empty(),
+            "Unresolved refs (NULL iid) should be excluded"
+        );
+    }
+
     #[test]
     fn test_explain_empty_activity() {
         let (conn, project_id) = setup_explain_db();