Upload Limits: Post Max Size vs Upload Max Filesize

1 min read

Overview #

Two PHP settings govern uploads: upload_max_filesize (the largest single file allowed) and post_max_size (the largest entire request allowed). A file is only as uploadable as the smaller of the two, and since every upload request carries form fields and overhead, post_max_size must be larger than or equal to upload_max_filesize. When it isn’t, large files fail even though they look allowed.

The Alert #

UPLOAD_LIMITS (warning): post_max_size is smaller than upload_max_filesize. Large uploads will fail with a size error.

What Breaks #

Scenario What happens
Media library uploads Files between the two limits are rejected (“exceeds maximum upload size”)
PDFs & large documents Client documents fail to attach
AI1WP .wpress files Migration/backup files are large by design and get refused
Form file uploads Fluent Forms file fields fail on big attachments

The Fix #

Set post_max_size to at least upload_max_filesize: on Xponent’s standard, both are 512M.

  • GridPane: control panel → PHP settings → Post Max Size and Upload Max Filesize, both set to 512M (Xponent does this for you).
  • php.ini / .user.ini:
    ini
    upload_max_filesize = 512M
    post_max_size = 512M

Verifying the Change #

Upload the file that previously failed. If it succeeds, both settings are aligned.

The Xponent Standard #

Xponent-managed sites run both at 512M: generous enough for large media and migration files, with post_max_size never the bottleneck.

Related Articles #

Updated on August 31, 2026