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WHMCS - The Complete Client Management, Billing & Support Solution
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Release Version: 9.0.1 (9.0.1-release.1)
Release Type: Maintenance Release
Distro Type: Patch Set
Release Date: 14 Jan 2026

PLEASE READ ALL THE ENCLOSED INSTRUCTIONS

Documentation: https://go.whmcs.com/1893/docs
Community Forums: https://whmcs.community/
Client Area: https://www.whmcs.com/members/
Support: https://www.whmcs.com/support/

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[ CONTENTS ]
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1. What is a Patch Set
2. Applying the Patch
3. Confirming a Successful Upgrade
4. Down for Maintenance
5. Further Help


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[ WHAT IS A PATCH SET ]
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Patch Sets contain only the files that have changed between the
immediate, previous version and the latest version, (ie. a patch set
for version 1.1.2 is valid for a 1.1.1 installation and nothing else).

We provide these to make updating both quicker and easier for those of
our customers who stay current and up-to-date with the latest WHMCS
releases. By including only the changed files, patch sets have less
files to upload which makes the upgrade process quicker and simpler
for you to perform.


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[ APPLYING THE PATCH ]
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IMPORTANT: Before you begin please ensure you are running the version
required by the patch. The version a patch set is designed for is
indicated by the first and smaller number in the zip download filename.

If you are not running the version indicated, please stop and use the
latest available full version (available from the WHMCS Members Area)
to upgrade instead.

1. Unzip the patch set files

i. For patches that have updates for the “admin” directory: If you
have renamed your "admin" directory, then make sure you rename
the /whmcs/admin directory to match.

2. Upload the files from the /whmcs/ directory to the root directory
of your WHMCS installation

3. Visit the admin area of your WHMCS installation to trigger the
version number bump and complete the process

No install or upgrade process is required.


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[ CONFIRMING A SUCCESSFUL UPGRADE ]
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To confirm an upgrade has been successfully applied, login to your WHMCS
admin area and check to make sure that the Version Number displayed
either on the admin homepage (in the sidebar of all default templates)
or in Help > Check for Updates is the version you attempted to apply.

If it has not incremented, then one or more of the files has not
uploaded successfully. You should double check file permissions and
attempt the steps again from the beginning.


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[ DOWN FOR MAINTENANCE ]
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If after uploading the files from a Patch Set you see a "Down for
Maintenance" or "Upgrade in progress..." warning message then this
indicates that the patch set files you attempted to apply are not
compatible with the version of WHMCS you were previously running.

To complete the upgrade you will need to download the latest Full
Release version and upgrade using the full version upgrade process
which can be found @ https://go.whmcs.com/790/updating


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[ FURTHER HELP ]
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For further help and information on upgrading, please visit our docs
site @ https://go.whmcs.com/790/updating

And of course our support team is always available to answer any
questions or concerns you might have when performing an upgrade. Simply
open a ticket @ https://www.whmcs.com/support/ and a member of our team
will get back to you.


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Thank you for choosing WHMCS.

