lein_error

Could not transfer artifact org.clojure:tools.nrepl:pom:0.2.6 from/to central (h
ttps://repo1.maven.org/maven2/): sun.security.validator.ValidatorException: PKIX
 path building failed: sun.security.provider.certpath.SunCertPathBuilderExceptio
n: unable to find valid certification path to requested target
This could be due to a typo in :dependencies or network issues.
If you are behind a proxy, try setting the 'http_proxy' environment variable.
Exception in thread "Thread-3" clojure.lang.ExceptionInfo: Could not resolve dep
endencies {:suppress-msg true, :exit-code 1}
        at clojure.core$ex_info.invoke(core.clj:4403)
        at leiningen.core.classpath$fn__5769.invoke(classpath.clj:185)
        at clojure.lang.AFn.applyToHelper(AFn.java:160)
        at clojure.lang.AFn.applyTo(AFn.java:144)