diff --git a/src/data/backwardsCompatibility/datatypeCleanup.js b/src/data/backwardsCompatibility/datatypeCleanup.js
index f9c1bda3a956e3f0a9309a537766eb1050559574..28eccd8f99025436345b5004d00bbf31c8f01705 100644
--- a/src/data/backwardsCompatibility/datatypeCleanup.js
+++ b/src/data/backwardsCompatibility/datatypeCleanup.js
@@ -1179,6 +1179,11 @@ globalThis.SlaveDatatypeCleanup = (function SlaveDatatypeCleanup() {
 		if (typeof slave.partners !== "object") {
 			slave.partners = new Set();
 		}
+		for (const partner of slave.partners) {
+			if (typeof partner !== "number") {
+				slave.partners.delete(partner);
+			}
+		}
 	}
 })();