Error 15104 generally indicates that QuickBooks is encountering a problem verifying the digital signature of the payroll update file or that a file necessary for the update process is missing or damaged. This digital signature is crucial for ensuring the authenticity and integrity of the update, confirming it originates from Intuit and hasn’t been tampered with. When this verification fails or a key file is absent, QuickBooks understandably halts the update process to safeguard your system.
