It is highly recommended to upgrade your ROMMON to at least 15.0(1r)M16 before jumping to the latest 15.7 releases to prevent "invalid image" flags. Fix/Recovery Steps:
Understanding the filename helps ensure you are using the correct image for your hardware: C1900-universalk9-mz-spa-157-3-m9-bin Fix Download
The IOS image is a universal software release for the Cisco 1900 Series Integrated Services Routers (ISR) . This specific version, 15.7(3)M9 , is a maintenance release that provides critical bug fixes and security enhancements for aging networking hardware. How to Properly Fix and Download the Image It is highly recommended to upgrade your ROMMON