Captcha BotDetect：意外的令牌<出现每隔一页刷新一次

Using Captcha BotDetect for Codeigniter 3 with ion auth

first load:

• normal output
• no error if submitted

if refreshed:

• captcha is displayed except for reload icon, probably crashed the remaining tasks after the error.
• error will appear if submitted

"Uncaught SyntaxError: Unexpected token <" appears in console every other refresh and still display some parts of the captcha on page but gives an error upon submit.

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to decode session object. Session has been destroyed

Filename: Session/Session.php

Line Number: 143