No resources available to start '%s' process. Use sp_configure to increase the number of user connections.
This error occurs when SQL Server is not configured with enough user connections to support all requests. There is one resource for each configured user connection. When all resources are in use and a request is made to create another process, error 1601 occurs.
Use the sp_configure system procedure to increase the number of user connections:
sp_configure 'user connections', new_value go
reconfigure with override go
Depending on the exact configuration of your SQL Server, each user connection requires a certain amount of memory, whether or not it is in use. Gradually increase the number of user connections until these errors no longer occur. When you change the user connections option, you might need to increase the memory option.
For additional information about configuring user connections, see Chapter 21, "Configuration Issues."