Sanjeev, I have the same error and unable to approve a user:
Argument 1 passed to timetable_phpmailer_init() must be an instance of PHPMailer, instance of WPMailSMTP\MailCatcherV6 given, called in /var/www/html/wp-includes/class-wp-hook.php
All my plugins are up to date including WordPress itself and the themes.
I tried to deactivate some plug-ins but no luck – email fails.
Thank you in advance for looking at it.
Here is the list of active plugins:
Advanced Editor Tools (previously TinyMCE Advanced)
Breadcrumb NavXT
Category Order and Taxonomy Terms Order
Change Memory Limit
Contact Form 7
Envato Market
GDPR Compliance & Cookie Consent
Google Analytics for WordPress by MonsterInsights
HubSpot All-In-One Marketing – Forms, Popups, Live Chat
MC4WP: Mailchimp for WordPress
Menu Image
New User Approve
NextGEN Gallery
Profile Builder
Redirection
Restrict Content
Slider Revolution
Smash Balloon Instagram Feed
Social Media and Share Icons (Ultimate Social Media)
SSL Insecure Content Fixer
STM Importer
STM Post Type
Timetable Responsive Schedule For WordPress
UpdraftPlus – Backup/Restore
WooCommerce
Wordfence Security
WP Mail SMTP
Yoast Duplicate Post
Yoast SEO