I regularly use a skyline analysis tool, but in recent 4-5 days I get error messages "ERROR 999999: Something unexpected caused the tool to fail. Contact Esri Technical Support (http://esriurl.com/support) to Report a Bug, and refer to the error help for potential solutions or workarounds".
Before that, I have successfully used the tool more effectively and smoothly. Now it is not stable. Any suggestions for this problem?