Many people often make this mistake when learning cookies. Someone asked me this question today, so I will share with you the solution to this problem (there is no specific solution on the Internet).
error code:

Cookie cookie=new Cookie("name","value value2");
response.addCookie(cookie);

Error
Java. Lang. IllegalArgumentException: An invalid character [32] was present in the Cookie value
Error code:

Cookie c=new Cookie("name","value,value2");
response.addCookie(c);

Error:
Java. Lang. IllegalArgumentException: An invalid character [44] was present in the Cookie value
…
the exception can be seen that this problem belongs to the invalid parameters, looking at the back of the prompt content
the An invalid character [44] was present in the Cookie value
cookies are invalid characters in character [44], so we query ASCII code is 44 said
“, “said 32 Spaces so we only need to replace the value of the corresponding characters, or coding