Everything about PHP

Subscriber holds one capability, Administrator all fifty. What the five WordPress user roles really grant, why code checks capabilities instead of role names, and how to build a role that fits the job.

The message means PHP ran, wp-config.php was read, and the connection to MySQL failed. Nothing more. Here is how to tell a wrong password from a downed server from a host that ran out of connections, and what to do about each.

Between the URL bar and WP_Query sits an ordered array of regular expressions, 247 of them on this blog, stored in a single option row. Paste yours in, walk a request path down them, and see which rule wins, what query it builds and why the 404 happens.

The permalink field decides thirteen URL shapes at once, and most of them fail quietly when you change it. What each structure tag costs, what verbose page rules actually do, which collisions core resolves first, and which old URLs its canonical redirect will never rescue.

The media library says 8 MB, the file is 12 MB, and nothing you edit in WordPress moves the number. It is not a WordPress setting at all: core reads two PHP directives and prints the smaller one. Which limit is really stopping the upload, why post_max_size is usually the culprit, how to raise the limits in the order that works, and why a photograph almost never needs a bigger ceiling.

WordPress has allowed .heic uploads since 6.7 and converts them to JPEG on the way in, but only when the server has a HEIC-capable Imagick. Here is what core actually does with the file, why the same site answers differently through a browser and through WP-CLI, and which fix stops the problem instead of managing it.

The "Allowed memory size exhausted" fatal error involves three separate ceilings, and the one most people raise is not the one that stopped the request. How PHP's memory_limit, WP_MEMORY_LIMIT and WP_MAX_MEMORY_LIMIT interact, and why images trigger the error more often than anything else.

ü is not corruption. It is one umlaut, two UTF-8 bytes, read by a program that believed they were Windows-1252, then saved again so the wrong reading became the content. Here is how to tell which wrong turn your text took, why copied replacement lists only half work, and what to check in the database before you clean anything.

A watermark can go on the original, on the sub-sizes WordPress generates, or on top at display time. Only two of those put pixels in the file, and only one of them is reversible.

wp-config.php is the first file WordPress reads that is specific to your install, and almost every fix you will ever be handed ends with "add this line to wp-config.php". Here is what the file actually does, which constants earn their place, and why the placement rule matters.