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Unknown collation: ‘utf8mb4_unicode_ci’

When trying to import MySQL dumps from newer servers to older servers you may get:


The quick and dirty solution is to do a search and replace on the database dump changing “utf8mb4_unicode_ci” and “utf8mb4_unicode_520_ci” to “utf8_unicode_ci”.

This can be accomplished with sed:


Partition Large Drive

The classic “fdisk” utility can’t create partitions larger then 2TB. The “parted” utility can be used instead as follows:



WordPress SSL Termination Fix

Add this code to wp-config.php to stop redirect loops caused by SSL termination on a proxy or load balancer:



Getting the CA Certificate Chain

Most SSL providers don’t include a complete CA certificate chain with their SSL certificate and it can be hard to track down the correct chain. There’s a great website for this purpose. Check out … just paste in the certificate and download the correct cert chain. I’ve used hundreds of times on many different SSL providers and it’s worked every time.


AccessControlAllowOrigin CORS Header With Multiple Domains

The AccessControlAllowOrigin CORS header does not allow multiple domains. This can be a problem in some cases. A workaround on the server is to detect the incoming Origin header, match against an allowed list and then generate the AccessControlAllowOrigin header using the domain. In Apache this can be accomplished with: