PHP 8.5 is Not Available on Ubuntu 25.10

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PHP 8.5 is the latest version of PHP, but you may encounter issues when trying to install it on Ubuntu 25.10 (Questing Quokka).

In this guide, we will explain why PHP 8.5 is not available on Ubuntu 25.10 and what you can do instead.

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Problem

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When attempting to install PHP 8.5 using the Ondřej Surý PHP repository, you may encounter errors such as:

E: The repository 'https://ppa.launchpadcontent.net/ondrej/php/ubuntu questing Release' does not have a Release file.

Or dependency errors like:

Unable to satisfy dependencies
php8.5 depends on php8.5-common but it is not going to be installed
libxml2 not installable

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Why This Happens

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1. PPA Does Not Support Ubuntu 25.10 Yet

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The Ondrej Sury PHP PPA does not yet provide packages for Ubuntu 25.10 (questing).
This means:

• No official PHP 8.5 packages for this release
• Repository returns 404 / missing Release file

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2. Incompatible Dependencies

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Even if you force the repository using Ubuntu 24.04 (noble):

• Ubuntu 25.10 uses newer system libraries
• PHP 8.5 packages are built for Ubuntu 24.04

This causes dependency issues such as:

• libxml2 version mismatch
• php8.5-common not installable
• Apache/FPM packages failing

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3. APT Security Restrictions

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APT blocks unsigned or incompatible repositories:

• Missing GPG keys
• Unsupported release files
• Signature verification failures

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Recommended Solutions

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Option 1: Use Default PHP Version (Recommended)

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Install the default PHP version available in Ubuntu 25.10:

apt install php -y

This installs:

• PHP 8.4 (fully supported)
• Compatible with all system libraries

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Option 2: Use Ubuntu 24.04 (Best for PHP 8.5)

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If you specifically need PHP 8.5:

• Use Ubuntu 24.04 LTS
• Fully supported by the Ondřej PHP repository
• No dependency issues

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Option 3: Use Docker (Advanced)

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Run PHP 8.5 in a container:

docker run -it php:8.5-cli php -v

This allows you to use PHP 8.5 regardless of host OS.

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Option 4: Wait for Official Support

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Support for Ubuntu 25.10 will be added once:

• PPA maintainer releases packages for questing
• Dependencies are aligned with the new system libraries

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Conclusion

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PHP 8.5 is currently not available for Ubuntu 25.10 due to:

• Lack of repository support
• Dependency incompatibilities

For best results:

• Use default PHP 8.4, or
• Use Ubuntu 24.04 for PHP 8.5

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Summary

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• Ubuntu 25.10 default PHP: 8.4
• PHP 8.5 support: ❌ Not available yet
• Recommended setup: Ubuntu 24.04 + PHP 8.5