diff --git a/src/network/utils.ts b/src/network/utils.ts
index ddbd48fc0..7b7cb212e 100644
--- a/src/network/utils.ts
+++ b/src/network/utils.ts
@@ -482,13 +482,37 @@ function fromError(error: any) {
     return wrappedError.toJSON();
   }
 
-  // If an error is not serialisable (for example, throwing Object.create(null))
-  // then trying to serialise it to a string would throw an error.
+  // Use the properties of the error to create an appropriate error message.
   let message = '';
+  switch (typeof error) {
+    case 'boolean':
+    case 'number':
+    case 'string':
+    case 'bigint':
+    case 'symbol':
+      message = `Non-error literal ${String(error)} was thrown`;
+    case 'object':
+      // Let the fallback handler catch null values.
+      if (error == null) break;
+      // If we have an error message defined, then return that.
+      if ('message' in error && typeof error.message === 'string') {
+        message = error.message;
+      }
+      // If present, mention the constructor name in the message.
+      if (error.constructor?.name != null) {
+        message = `Non-error object ${error.constructor.name} was thrown`;
+      }
+      // Any other values should be handled by the fallback handler.
+      break;
+  }
+
+  // Handle cases where the error is not serialisable, like objects created
+  // using Object.create(null). Trying to serialise this throws a TypeError.
   try {
-    message = `Unexpected error occured: ${error}`;
+    message = `Non-error value ${String(error)} was thrown`;
   } catch (e) {
-    message = 'Unexpected error occured';
+    if (e instanceof TypeError) message = 'Non-error value was thrown';
+    else throw e;
   }
 
   // If the error was not an Error, then wrap it inside ErrorPolykeyUnexpected