Content Index Rebuilding not working in Confluence 6.15.4

[Akshay Gupta]

Unable to find users in search tabs, team calendar, cannot tag users.

Unable to build the Content index.

I tried the document: Removing and Rebuilding indexing from scratch
how-to-rebuild-the-content-indexes-from-scratch

But the application gives errors and indexing don't start. I clicked on the build button, but nothing happens

Error for Reference: 

2019-07-22 23:32:13,264 ERROR [https-jsse-nio2-443-exec-1] [common.error.jersey.ThrowableExceptionMapper] toResponse Uncaught exception thrown by REST service: com/atlassian/gzipfilter/org/apache/commons/lang/StringUtils
-- referer: https://itdocs.intranet.mckinsey.com/admin/search-indexes.action | url: /rest/goedit/1.0/license/status.json | traceId: 447d09f7d8b76ed9 | userName: Akshay Gupta
java.lang.NoClassDefFoundError: com/atlassian/gzipfilter/org/apache/commons/lang/StringUtils
at de.kontextwork.goedit.GoeditSettingsContainer.getApiKey(GoeditSettingsContainer.java:29)
at de.kontextwork.goedit.GoEditLicense.loadLicenseInfo(GoEditLicense.java:97)
at de.kontextwork.goedit.GoEditLicense.<init>(GoEditLicense.java:43)
at de.kontextwork.goedit.rest.GoeditResource.licenseStatus(GoeditResource.java:248)
at sun.reflect.GeneratedMethodAccessor1923.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
......

.....

[Nic Brough _Adaptavist_]

It looks to me like you have an app installed called "go edit", and the licence for it has expired or been removed.  You'll need to remove the app completely, or get a new licence for it, then re-index.