Most importantly for developers: was not binary compatible with ObjectARX 2008. Any ARX module compiled for AutoCAD 2008 (32-bit) would fail to load in AutoCAD 2010 64-bit, returning the infamous error: “acrxLoad: failed to load civilcad.arx – is incompatible with this version of AutoCAD.”
Autocad 2010 Compatibility with Windows 10 - Forums, Autodesk civilcad 2008 para autocad 2010 64 bits
Engcorp (later AltaGIS) eventually released and CivilCAD 2012 with 64-bit support for AutoCAD 2010–2012. However: Most importantly for developers: was not binary compatible
Step 3: Path ConfigurationDuring installation, ensure the destination path matches the AutoCAD 2010 64-bit installation folder (usually C:\Program Files\AutoCAD 2010). If the installer defaults to Program Files (x86), you must manually change it to the standard Program Files directory. If the installer defaults to Program Files (x86),
No patch, crack, or compatibility setting can overcome the 32-vs-64-bit and ObjectARX version barriers.