Public bug reported:
# Bug Report: nginx 1.24.0-2ubuntu7.16 Regression - "no buffer space in
script copy"
## Summary
Ubuntu security update `nginx 1.24.0-2ubuntu7.16` (noble-security) introduces a
regression causing `alert` level errors: `no buffer space in script copy` when
using FastCGI with PHP-FPM over HTTP/2.
## Environment
- OS: Ubuntu 24.04.4 LTS (Noble Numbat)
- nginx: 1.24.0-2ubuntu7.16 (broken) → 1.24.0-2ubuntu7.15 (works)
- PHP-FPM: 8.4 and 7.4
- Protocol: HTTP/2 with SSL
## Error
```
2026/08/19 20:34:46 [alert] 19458#19458: *65 no buffer space in script copy
```
Occurs on:
- `/wp-admin/` dashboard pages
- `/wp-admin/load-scripts.php`
- `/wp-admin/load-styles.php`
- `/wp-json/el/v2/members/list` (REST API)
- `/wp-cron.php` background jobs
Returns HTTP 500 to clients.
## Reproduction
1. Fresh Ubuntu 24.04 install
2. Install nginx 1.24.0-2ubuntu7.16 + php8.4-fpm
3. Configure WordPress with FastCGI (standard nginxconfig.io config)
4. Access any wp-admin page over HTTP/2
5. Observe "no buffer space in script copy" alerts in error.log
## Workaround
Downgrade to 1.24.0-2ubuntu7.15:
```bash
apt-get install -y --allow-downgrades \
nginx=1.24.0-2ubuntu7.15 \
nginx-common=1.24.0-2ubuntu7.15 \
nginx-core=1.24.0-2ubuntu7.15 \
libnginx-mod-http-image-filter=1.24.0-2ubuntu7.15 \
libnginx-mod-http-xslt-filter=1.24.0-2ubuntu7.15 \
libnginx-mod-mail=1.24.0-2ubuntu7.15 \
libnginx-mod-stream=1.24.0-2ubuntu7.15
```
## Configuration (minimal)
```nginx
# nginx.conf
worker_rlimit_nofile 524288;
events { worker_connections 4096; }
http {
client_body_buffer_size 128k;
client_max_body_size 100m;
}
# php_fastcgi.conf
fastcgi_buffers 64 64k;
fastcgi_buffer_size 128k;
fastcgi_max_temp_file_size 1024m;
fastcgi_busy_buffers_size 128k;
fastcgi_buffering off;
fastcgi_request_buffering off;
```
## Analysis
The issue appears to be in nginx's FastCGI buffer management
(`ngx_http_fastcgi_copy_buffer`) when handling HTTP/2 streams. The `1.16`
security update may have changed buffer allocation logic. Disabling buffering
(`fastcgi_buffering off; fastcgi_request_buffering off;`) mitigates but doesn't
fully resolve it in 7.16.
## Files Changed in 7.16
Please review the changelog/diff between 7.15 and 7.16 for FastCGI/HTTP/2
related changes.
## Reporting
- Ubuntu Launchpad: https://bugs.launchpad.net/ubuntu/+source/nginx/+filebug
- nginx Trac: https://trac.nginx.org/nginx/newticket
- Security: [email protected] (if deemed security-relevant)
## Impact
High - breaks WordPress/WooCommerce admin panels and REST APIs on Ubuntu 24.04
LTS after security update.
** Affects: nginx (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2164558
Title:
nginx 1.24.0-2ubuntu7.16 regression: "no buffer space in script copy"
with FastCGI/HTTP/2
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