diff --git a/changes/708.bugfix.rst b/changes/708.bugfix.rst
new file mode 100644
index 000000000..b3dbf127d
--- /dev/null
+++ b/changes/708.bugfix.rst
@@ -0,0 +1 @@
+Fixed error on first run after iOS simulator update.
diff --git a/src/briefcase/integrations/subprocess.py b/src/briefcase/integrations/subprocess.py
index 31c751db4..c30dc5f6a 100644
--- a/src/briefcase/integrations/subprocess.py
+++ b/src/briefcase/integrations/subprocess.py
@@ -44,7 +44,7 @@ def json_parser(json_output: str) -> JsonT:
     :param json_output: command output to parse as JSON
     """
     try:
-        return json.loads(json_output)
+        return json.loads(json_output[json_output.index("{") :])
     except json.JSONDecodeError as e:
         raise ParseError(f"Failed to parse output as JSON: {e}") from e