Event Calendar got 500 error

Table of Contents

Symptom

Event Calendar stop working.

/events/, and event page shows 500 error.

/contact/ page shows 500 error.

Problem

.htaccess file was changed.

Working file:

# HTTPS forced by SG-Optimizer
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{SERVER_NAME}%{REQUEST_URI} [R=301,L]
</IfModule>
# END HTTPS
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

It was changed to

# This file was updated by Duplicator on 2019-12-30 00:19:21. See .htaccess.orig for the original .htaccess file.
# Please note that other plugins and resources write to this file. If the time-stamp above is different
# than the current time-stamp on the file system then another resource has updated this file.
# Duplicator only writes to this file once during the install process while running the installer.php file.

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /s/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /s/index.php [L]
</IfModule>
# END WordPress