diff --git a/CHANGES b/CHANGES
index 5f6bbaf8d..94f7fce05 100644
--- a/CHANGES
+++ b/CHANGES
@@ -16,6 +16,8 @@ Features added
 Bugs fixed
 ----------
 
+* #5320: intersphinx: crashed if invalid url given
+
 Testing
 --------
 
diff --git a/sphinx/ext/intersphinx.py b/sphinx/ext/intersphinx.py
index 372f7baab..88e9997eb 100644
--- a/sphinx/ext/intersphinx.py
+++ b/sphinx/ext/intersphinx.py
@@ -403,14 +403,19 @@ def inspect_main(argv):
         def warn(self, msg):
             print(msg, file=sys.stderr)
 
-    filename = argv[0]
-    invdata = fetch_inventory(MockApp(), '', filename)  # type: ignore
-    for key in sorted(invdata or {}):
-        print(key)
-        for entry, einfo in sorted(invdata[key].items()):
-            print('\t%-40s %s%s' % (entry,
-                                    einfo[3] != '-' and '%-40s: ' % einfo[3] or '',
-                                    einfo[2]))
+    try:
+        filename = argv[0]
+        invdata = fetch_inventory(MockApp(), '', filename)  # type: ignore
+        for key in sorted(invdata or {}):
+            print(key)
+            for entry, einfo in sorted(invdata[key].items()):
+                print('\t%-40s %s%s' % (entry,
+                                        einfo[3] != '-' and '%-40s: ' % einfo[3] or '',
+                                        einfo[2]))
+    except ValueError as exc:
+        print(exc.args[0] % exc.args[1:])
+    except Exception as exc:
+        print('Unknown error: %r' % exc)
 
 
 if __name__ == '__main__':