Site Feed can't be Activated

Question

I can't make "Site Feed" activated from Managed Site Features. It says

An unexpected error has occurred.

I get logs with

get-splogevent -starttime (get-date).addminutes(-1) | fl message > c:\errors.txt

Here is the error:

viewstatelog: Failed to write to the velocity cache

Edited:

I think I found the solution for this error. I write these commands at Powershell:

$instanceName ="SPDistributedCacheService Name=AppFabricCachingService"
$serviceInstance = Get-SPServiceInstance | ? {($_.service.tostring()) -eq $instanceName -and ($_.server.name) -eq $env:computername}
$serviceInstance.Provision()

But It says there is no available memory for Provision().

How can I clear cache?