Change FARM Account Password in Central Admin Server

Login to Central Admin server and open SharePoint Management Shell as administrator.

Run the below command (Replace Credentials with your new Credentials of the farm)

stsadm -o updatefarmcredentials -userlogin sp\<Account Name>  -password <Account Password>

Have Fun :)

The crawler could not communicate with the server. Check that the server is available and that the firewall access is configured correctly

Error while crawling content source in SharePoint 2013 search.

Resolution : Check the default search crawl account.

Sideloading of apps is not enabled on this site

In order to publish a SharePoint hosted apps
create a developer site in which developer feature enabled on it.
to publish a app on normal site enable developer on it. it's a hidden feature to be enabled from powershell.

Enable-SPFeature e374875e-06b6-11e0-b0fa-57f5dfd72085 –url <site URL>