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10.1.03 CORE Generator - Opening a core customization GUI results in "ERROR: sim:166 - An internal error has occurred. Closing core customization GUI."
When I attempt to create ("customize") some cores, including FIFO Generator 4.4 and Block Memory Generator 2.8, the following error occurs: "ERROR:sim:166 - An internal error has occurred. Closing core customization GUI. An Error occurred during Customization."
This issue occurs in ISE 10.1 with service pack 3 (SP3) installed and IP Update 3 not installed. Installing the IP update should resolve the problem. The IP Update can be downloaded from the Download Center: http://www.xilinx.com/support/download/index.htm In some cases, IP Update 3 does not successfully write to the $XILINX\lib\nt directory. If you have already installed IP Update 3 for ISE 10.1, use "libIp_Xst.dll" in the ISE backup install directory to replace the version in $XILINX\lib\nt.