A Microsoft SharePoint Server State Service error occurred while processing your request. For more information, contact your server farm administrator in SharePoint 2010

I checked many blogs, everybody telling that -
 
1. SQL server doesn't have enough space to process request, but the answer is partly correct. Not every time we shouldn't blame SQL server team... it's just guess.
2. Somebody telling that, Run "Farm Configuration Wizard". Don't ever do that, if you are already provisioned service applications with different settings.(not with default settings). Run "Farm Configuration Wizard" when you farm belongs to 'single server farm'. This trick will not work with multi server farm.
 
Then how do we resolve?
 
Check following settings in CA
 
1. Check wheather 'State Service' has been provisioned or not in CA. CA--> Manage Service Applications--> Check State Service existence.
 
2. Go to respective web application and click on 'Service Connections' on the ribbon. Check whether 'State Service' is part of assiciations or not?

 
3. If not, associate the State service app.

4. If already associated, choose 'Custom' and select all service applications and save settings.

that's it done!!!.

Note: Above steps don't resolve, follow below steps

1. Go to the WFE server where state service provisioned ---> IIS 7.0 --> Recycle respective app pool for the State service.