Plugin not working after upgrading to Wordpress 4.9.1

[jeremys6]

It used to work perfectly,
It suddenly stoped after upgrading to Wordpress 4.9.1
The error i get is
{"code":"rest_cannot_create","message":"Sorry, you are not allowed to create posts as this user.","data":{"status":401}}

[terriann]

I was also able to reproduce this issue - it seems to be caused by characters in the user's password. Didn't get a chance to dig deeper; just noticed inconsistencies between some accounts working and some failing followed by examining and testing the differences between the accounts.

Passwords that did not work:

• &poV9xtbvqzI@Z7fgxZWVfmg
• poV9xtbvqzI+Z7fgxZWVfmg

Passwords that did work:

• poV9xtbvqzIZ7fgxZWVfmg
• MSv382WarLWmSoqnh1vCma

Work Around: Remove non-alphanumeric characters from password.

[hypgfrch]

Under WordPress 4.9.9 as of today, Installed manually by placing the files at 'plugins' WP folder, successfully activated by pressing "activate", and successfully tested by authenticating through 'curl'.

My password contains non-alphanumerics.