Try the pfctl_table_op and set http code accordingly

jail2ban/__init__.py

@@ -88,10 +88,17 @@ def create_app():
         name = untaint(PAT_NAME, name)
         app.logger.info(f'Flushing table f2b-{name}'
                         f' in anchor f2b-jail/{remote_user}')
+        try:
             res = pfctl_table_op('f2b-jail/{remote_user}',
                                  table='f2b-{name}',
                                  operation='show',
                                  verbose=True)
+        except CalledProcessError as err:
+            if err.stderr.find(b'pfctl: Table does not exist.') > 0:
+                res = []
+            else:
+                raise err
+
         result = [entry.groupdict() for entry in
                   re.finditer(_PFCTL_TABLE_PAT,
                               '\n'.join([x.decode('ascii') for x in res]),
@@ -100,7 +107,7 @@ def create_app():
         return jsonify({'anchor': f'f2b-jail/{remote_user}',
                         'table': f'f2b-{name}',
                         'operation': 'list',
-                        'result': result })
+                        'result': result }), 200 if len(res) else 404
 
     @app.route("/register", methods=['PUT', 'DELETE'])
     @auth.login_required