I upgraded magento 2.1.4 to 2.3.5p1. I first upgraded it to 2.2.3 and then to 2.3.5 through command line.
After upgrade, I am getting Fatal error: Uncaught InvalidArgumentException: Unable to unserialize value. Error: Syntax error in /var/www/production/vendor/magento/framework/Serialize/Serializer/Json.php:39 on frontend and unable to run any magento command in terminal.
In terminal it gives error - "Unable to unserialize value. Error: Syntax error"
Please provide a solution to this.
Checked all permissions and ownership also.