Could not get user properties while publishing a blog post in AEM communities




am working on AEM communities and i was having an issue that when i try publishing a new blog post on my local system, i see an error in logs saying that "Could not get user properties" and few more exceptions i seen while debugging error.log file

POST /content/test/en/blog/jcr:content/mainPar/journal.social.json HTTP/1.1] com.adobe.cq.social.commons.comments.endpoints.AbstractCommentOperationService host posted a comment with an unknown userIdentifier (rsamala)

POST /content/test/en/blog/jcr:content/mainPar/journal.social.json HTTP/1.1] com.adobe.cq.social.srp.internal.UGCCResourceProvider Could not get user properties.

[Thread-15] com.adobe.cq.social.commons.ugclimiter.impl.UGCLimiterServiceImpl Social event has empty actor.

does any one know why am seeing this Exception ?

Thank in advance.