Permalink changed, how to avoid 404??

You can add the following code to your .htaccess file, before RewriteCond %{REQUEST_FILENAME} !-f:

RewriteRule /[a-zA-Z0-9_-]+/([0-9]+) /index.php?p=$1 [R=301,L]

Not sure it will work though.

Thanks it worked, but with a little modification to your code:

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule /[a-zA-Z0-9_-]+/([0-9]+)$ /index.php?p=$1 [R=301,L]

Thanks ??

Ahh, you should also add /? before $, just in case*.
Links with trailing (forward)slash wouldn’t work.
https://wael.nasreddine.com/linux/tip/19/

Thanks for the TIP ??

Is this a generic fix? I just read this:

“The best time to set up ‘Pretty Permalinks’ is the moment you install your blog because if you already have a bunch of existing posts, changing the permalink structure will make it so that your old links to those posts will result in page not found errors – to fix this you would need to edit the .htaccess file to set up permanent redirects for each post and page in the form of:
Redirect 301 https://www.yoursite.com/index.php?p=2 https://www.yoursite.com/the-new-post-title.htm”
(source)

Is this solution solving the problem he is addressing?

I tried the following and got a 404 error when trying to use .htm or .html

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wp/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule /[a-zA-Z0-9_-]+/([0-9]+)$ /wp/index.php?p=$1 [R=301,L]
</IfModule>

# END WordPress

Still need something that works with version 2.5.1

Thanks!
Leslie