RewriteCond: bad flag delimiters

I was getting this error while restarting Apache:

RewriteCond: bad flag delimiters

In this particular case this happen after editing the apache .conf files where Certbot added some redirects.

Short answer

This can be caused by a space in certain Apache config lines, e.g before the SERVER_NAME or HTTP_HOST

Good

RewriteCond %{SERVER_NAME} =www.example4.com

Bad

RewriteCond %{SERVER_NAME} = www.example4.com

Still bad but with quotes

RewriteCond %{SERVER_NAME} = "www.example4.com"

---

More detailed answer

service httpd restart
Redirecting to /bin/systemctl restart httpd.service
Job for httpd.service failed because the control process exited with error code.
See "systemctl status httpd.service" and "journalctl -xeu httpd.service" for details.

journalctl -xeu httpd.service
...
httpd[748100]: AH00526: Syntax error on line 29 of /etc/httpd/conf.d/vhosts.conf:
httpd[748100]: RewriteCond: bad flag delimiters
...

This was my full code and it was caused by the space after the "= "

RewriteEngine on
RewriteCond %{SERVER_NAME} = example4.com [OR]
RewriteCond %{SERVER_NAME} = www.example4.com

RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]

Correct code

RewriteEngine on
RewriteCond %{SERVER_NAME} =example4.com [OR]
RewriteCond %{SERVER_NAME} =www.example4.com

RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]

What is interesting is that it doesn't seem to work even if you wrap domain name around "quotes", also note Apache has no problem if you have spaces BEFORE the "=".