Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached
I've been using the DAAB for some time with no issues at all, until today. I had a customer go live and within a few hours I had the above error.
I fixed it by editing my connection string to explicitly specify connecion pooling, that fixed it.
<add name="PHSB" connectionString="Pooling=yes;Max Pool Size=100;Min Pool Size=5;server=HS-GODZILLA;database=PHSB;Integrated Security=true" providerName="System.Data.SqlClient"/>