Ensure you trust the file in your security settings if it was previously blocked. Incompatibility is a major factor in validation errors.
: Some custom apps require a jailbroken device; if the device is not jailbroken, the validation will fail. 3utools installation package validation failed
The "Installation package validation failed" error in 3uTools typically occurs during the installation of custom apps (IPA files), jailbreak attempts, or firmware updates. It indicates a breakdown in communication between the software, the device, and Apple's verification servers, or it may be triggered by security software on your computer. Ensure you trust the file in your security
: On your iPhone/iPad, go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings . if the device is not jailbroken