Have you updated your Operating system to El capitan? If yes, Please follow the below steps:
2. Go to Finder. click on Go > click on Go to Folder> then type ~library
3. Go to Application Support > Select Adobe folder> Choose File > get info and add admin, system and your username with Read and write permissions.
4. Give Permission to Adobe Lightroom Application under Application folder
5. Restart Lightroom and check whether its still crashing while tethered shoot or not.
If you have not updated your Operating system please follow the below article to troubleshoot tethered capture:
It is known bug of el capitan and Lightrom 6.2 or 2015.2 , here is the kbArticle for it
Update to Lightroom 6.3 or 2015.3 some issue with el capitan are resolved but still regarding tethering issue is still there