diff --git a/src/pages/how-to/monitor-system-and-network-activity.mdx b/src/pages/how-to/monitor-system-and-network-activity.mdx
index 840f27c2..df95b191 100644
--- a/src/pages/how-to/monitor-system-and-network-activity.mdx
+++ b/src/pages/how-to/monitor-system-and-network-activity.mdx
@@ -18,6 +18,12 @@ You can also use the search bar to filter events by activity type.
     The future versions will support connection events that occur in NetBird agents (e.g., peer A connected to peer B).
 </Note>
 
+<Note>
+    The <b>unknown</b> name or <b>unknown@unknown.com</b> e-mail address.
+    In the activity event store, the system keeps the deleted user information encrypted. If the encryption key has been corrupted or lost, then the events returned by the API could show "unknown@unknown.com" for the e-mail address field and "unknown" for the name field.
+    If the configuration files have been generated by the <b>configure.sh</b> script, you can find the previous encryption key in the backup files in the same folder as the script. Look for the <b>DataStoreEncryptionKey</b> field in the management.json backup file.
+</Note>
+
 ## Get started
 <p float="center" >
     <Button name="button" className="button-5" onClick={() => window.open("https://netbird.io/pricing")}>Use NetBird</Button>