Windows 3.1 released April 6, 1992
Windows 3.1 was released on April 6, 1992 as the successor to Windows 3.0. It provided a graphical user interface that ran on inexpensive ordinary PCs.
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The article discusses whether there were Windows 3.1 programs so incompatible with Windows 95 that patching them was pointless. It references a "permanently ineligible list" of applications that couldn't be made compatible with the new operating system.