Multisite returning 'Error establishing DB connection..." when popular site is hit hard.

I run a few different client sites on a WordPress Multisite hosted on a 'premium' dedicated VPS server on Bluehost. This has been working very well for me.

One of my clients sites,, is very popular. She will often link to her site from Facebook. At times the site will get a good amount of traffic and she will notify me that she is getting the "Error establishing DB connection".

To solve this problem I upgraded my server on Bluehost when this was first happening and it seemed to fix it. I recently put a forum on the site and when she shared it yesterday she started hearing from users who were getting the error.

I was not notified that the site was down at all (via pingdom, new relic, or the wordpress monitor from jetpack).

I'm self taught so any advice is much appreciated! Please let me know if I'm doing something totally wrong here or how I can prevent this error.

I am considering using the WPMU Multi DB plugin.


  • Alexander
    • DEV MAN’s Mascot

    Hi @Pete,

    Are you nearing thousands of sites? If so, might be a good time to switch to Multi-DB before getting too big.

    You could start by introducing some page cacheing. WP Super Cache is a good choice for this:

    This would reduce the number of DB queries, but cacheing periodic page loads into static files. The new visitors hit the static files instead of requiring more DB queries.

    It might also simply be that the forum has been added. That can introduce dozens more page requests and database queries. In fact, it would probably be better for this site to be on it's own database, or even it's own WordPress installation.

    Best regards,

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