Can not compile LESS anymore. Stange issue with anonymous-file-0.less

If I try to compile LESS files, I have this error showing up:

templates/t3_bs3_blank/less/template.less ParseError: missing closing `}` in anonymous-file-0.less on line 4623, column 16 4621| border-bottom: none; 4622| } 4623| #less-file-path{content: "templates/t3_bs3_blank/less/template.less";} 4624| 4625| 4626|

Can anyone tell me where I have to look for the missing closing "}" ? Whats that anonymous-file-0.less?