After upgrading PHP to 7.4 FastCGI I'm getting these errors:

: fread(): read of 8192 bytes failed with errno=21 Is a directory in example/wp/wp-includes/functions.php on line 5977

And:

Warning: Cannot modify header information - headers already sent by (output started at example/wp/wp-includes/functions.php:5977) in example/wp/wp-admin/admin-header.php on line 9

I have 3 plugins all disabled.

After upgrading PHP to 7.4 FastCGI I'm getting these errors:

: fread(): read of 8192 bytes failed with errno=21 Is a directory in example/wp/wp-includes/functions.php on line 5977

And:

Warning: Cannot modify header information - headers already sent by (output started at example/wp/wp-includes/functions.php:5977) in example/wp/wp-admin/admin-header.php on line 9

I have 3 plugins all disabled.

• php
• errors

• Is your copy of WP up to date and unmodified? That line is a comment in the latest version of that file, not an fread call github/WordPress/WordPress/blob/master/wp-includes/… – Tom J Nowell ♦ Commented Jun 24, 2020 at 21:08
• This has an official bug report at core.trac.wordpress/ticket/49979, I recommend registering on WP Trac and leaving feedback indicating your setup and that you too have that issue – Tom J Nowell ♦ Commented Jun 24, 2020 at 21:09
• @TomJNowell It's been a few months but I think it has to this plugin wordpress/plugins/wp-hashed-ids. The plugin works fine in normal wordpress but causes errors in Network Wordpress (WPMU). – 1.21 gigawatts Commented Sep 28, 2020 at 19:36

1 Answer 1

That sounds like a theme problem, since you have all plugins disabled. The theme has some error, possibly some extra spaces at the top of a file.

I'd change to one of the 'Twenty' themes and see if the problem stops. If so, contact your theme's support area.

If problem persists with one of the "Twenty" themes active, then I'd try a re-install/re-update of the WP core code, using the Admin, Updates screen.