Rockwell actually provides pre-built virtual images for partners, but you must build your own for V20.04 using a legitimate Windows 7 license.
: The major version of the software must match the major version of the firmware on your PLC controller. For version 20.xx software, the controller must be running firmware 20.xx. When a program is opened in a different major version, RSLogix prompts for a firmware update before allowing offline editing or online connection. Rslogix 5000 Version 20.04 Download
: The license file is missing or pointing to an expired server directory. When a program is opened in a different
Open the "FactoryTalk Activation Manager" from the Start Menu. Select "Get Activations." Select "Get Activations
Which (e.g., ControlLogix 1756, CompactLogix 1769) are you connecting to?
Why the ".04" sub-version? Rockwell’s revision history is littered with minor builds that fixed critical, catastrophic bugs. Version 20.01 had a notorious issue with producing/consuming tags over EtherNet/IP that led to unexpected connection closures. Version 20.03 introduced a compatibility glitch with Windows 10. is the "golden build"—the one that plays nicely with Windows 10 Enterprise LTSC, handles ASCII serial communications without buffer overflow, and, most importantly, contains the final approved EDS files for now-obsolete third-party drives.
To understand why V20.04 is so sought after, you need to understand the chronology of Rockwell’s software evolution.