I will try and make this answer not as vauge as the question posted and the error message given by Sharepoint 2013.
I found that there were two issues related to adding new posts to a newsfeed or microblog.
1. A hidden feature had to be activated on the site
[Enable-SPFeature -Identity 6928B0E5-5707-46a1-AE16-D6E52522D52B -Url http://intranet/sites/TestNewsfeed]
2. Add permissions for service account user to access user profile data
- Open Central Administration, then
- Manage Service Applications
- Highlight the User Profile service application link, but don’t click it link! Click on the whitepace with no text. Microsoft have made these links context aware!!
- In the “Sharing” group of the ribbon, click “Permissions”
- In this prompt, put in your service account that is running your Distributed Cache, and grant it full control.
Last thing to consider is that performing this action may cause the User Profile Services web services to be restarted, if the farm is in use then perform steps after hours.