Dear concern,
By mistake /opt/gitlab and /var/opt/gitlab file and folder permissions had changed. After that I have changed permissions of file and folder to orignal permissions . But after that when I open mattermost chat url in browser, nothing shows , only blank page show in browser web page in some PC and in some PC mattermost chat opens in browser and user can login to it. All PCs are in same network.
Please help me to find the solution.
After checking log, a postgresql file permission was changed so mattermost log was showing permission denied of that file. After applied wright permission on that file, mattermost started working fine.