We introduced a change on packages.magento.com that had the unintended result of causing errors with certain Magento packages.

This affects only users who used composer create-project to create their Magento project between the dates of August 13 and August 17, 2015.

A user reported one symptom on GitHub about an error that occurred during the installation:

[UnexpectedValueException]
The checksum verification of the file failed (downloaded from https://packages.magento.com/_packages/magento_framework-1.0.0-beta.zip)

The cause is a conflict between packages on packages.magento.com compared to the local Composer cache. To resolve the issue, clear your Composer cache as follows:

1. Log in to your Magento server as a user with permissions to run composer in the Magento installation directory.
2. cd <your Magento install dir>
3. Enter composer clear-cache