The following are known issues with this release:

Blocks

• In the Block Properties table, you cannot enter a combination of decimals and fractions. All numerical values must be either decimals or fractions.

Dimensional Constraints

• Dimensional constraints do not behave as associative dimensions when opened in previous versions of AutoCAD. To reassociate dimensions, use the DIMREASSOCIATE command.

Hatch

• By default, a preview of the hatch displays as you move your mouse over bounded areas. To improve the response time in large drawings, turn off the hatch preview feature with the HPQUICKPREVIEW system variable.

Materials

• Do NOT change the default location of the installed Materials2011 folder. Changing the default location of this folder may cause unpredictable results.
• When you install AutoCAD 2011, by default, the Autodesk Material Library is also installed. In AutoCAD 2011, AutoCAD 2010 drawings may display with lower resolution textures. This is because the Autodesk Material Library 2011 has lower resolution than the Autodesk Material Library 2010. For image fidelity, install the Autodesk Material Library 2011 Medium Image Library. In the AutoCAD 2011 installation wizard, on the Select Products to Install page, select Autodesk Material Library Medium Image Library.
• HDR and EXR files are not supported even though the format displays in the Materials Editor. If you use materials in these formats, your drawing will render as all black.
• In the Duplicate Appearance Name dialog box, if you select Replace, the material is not replaced in the Materials Library as expected. To workaround, in the Duplicate Appearance Name dialog box, select Keep Both.
• If you create a Material library on a network computer, you must restart AutoCAD to make it available on your network. If you do not and attempt to use the file on other network computers, an error displays and you cannot open the file.

Polylines

• Autoconstraining a polyline that has many points may significantly reduce AutoCAD performance.

Rotating Constrained Geometry

• Rotating horizontally or vertically constrained geometry may give unpredictable results.

Toolclips

• On Windows XP (64-bit), toolclips (videos within tooltips) do not display.

Transparency

• The transparency property of objects is ignored when exporting to WMF, SAT, STL, EPS, DXX, or DGN formats.
• The effect of locked layer fading and other fading effects (xrefs, images, DWF and DGN underlays) is cumulative with object-based transparency. As a result, objects that use both fading and transparency may be difficult to see.