The error message is a common hurdle when updating PrestaShop using the 1-Click Upgrade module. This integrity check fails when the file downloaded to your server doesn't perfectly match the unique "fingerprint" (MD5 hash) provided by the PrestaShop repository. Common Causes of MD5 Mismatches
When this error occurs, it indicates that the file on your server is either incomplete, corrupted, or different from the official release. prestashop download complete but md5 sum does not match