Home / Fixing WordPress / Cannot install or update plugins or themes after core 6.4 update
I have several sites where plugins or themes cannot be installed or updated after the 6.4 core update. The error shown is: Installation failed: 500 Internal Server Error
Re the 500 error, errors like this are logged. Check the error log on your server. If you can’t find the log, please contact your host.
Meantime, enable wp_debug and wp_debug_log and after an error, look at wp-content/debug.log to see if anything gets logged there. https://wordpress.org/support/article/debugging-in-wordpress/
You can also try this: Please attempt to disable all plugins, and use one of the default (Twenty*) themes. If the problem goes away, enable them one by one to identify the source of your troubles.
If you cannot access wp-admin, there are other ways to deactivate plugins: https://wordpress.org/support/article/faq-troubleshooting/#how-to-deactivate-all-plugins-when-not-able-to-access-the-administrative-menus
Seems to be related to.
This is the error message in the logs:(110)Connection timed out: mod_fcgid: ap_pass_brigade failed in handle_request_ipc function, referer: https://mysite.uk/wp-admin/update-core.php?action=do-plugin-upgrade
Deactivated all plugins and tried to install a new plugin and this is the error message: End of script output before headers: admin-ajax.php, referer: https://mysite.uk/wp-admin/plugin-install.php
Hi @ddrj, it’s the bug @lukefiretoss mentioned
https://github.com/WordPress/Requests/pull/657/files
Works for me after reverting the changes above, the file is in wp-includes/Requests/src/Transport/Curl.php
Thanks @kesar1 that solved the issue
Glad to be of assistance 🙏
I see the same error, appears during “upgrade network” on my multisite install. Can you be more specific about the fix? Is this an issue that presumably WP.org will fix in the next patch?
6.4.1 is coming soon. See https://make.wordpress.org/core/2023/11/08/wordpress-6-4-1-rc1-is-now-available/
