What this error means
The application failed to obtain a database connection — either it cannot connect to the database at all, or it did not receive a free connection within the timeout period.
👉 This typically indicates a PostgreSQL outage, unavailability, or overload.
How the issue manifests
One of the following variants may appear in the log or in the application's error message. They all mean the same thing:
class java.sql.SQLException:
Connections could not be acquired from the underlying database!
class java.sql.SQLException:
An attempt by a client to checkout a Connection has timed out.
class com.mchange.v2.resourcepool.TimeoutException:
A client timed out while waiting to acquire a resource from
com.mchange.v2.resourcepool.BasicResourcePool -- timeout at awaitAvailable()
Possible causes
the database service is not running
the connection was interrupted (network issue, server restart, terminated VPN)
the database is overloaded or not responding
available connections have been exhausted (too many clients or integrations connected at the same time)
How to resolve the issue
The procedure differs depending on where you run Flexi.
Cloud (address in the format companyname.flexibee.eu)
You do not have access to the database or the server — their operation is managed by ABRA. Try repeating the action, and if the issue persists, contact support. Please include the exact error message and the time it occurred.
Your own server (on-premise)
Verify that the PostgreSQL database service is running.
Check the server's availability from the client machine (network, port, firewall).
Review the server log and the PostgreSQL log — they usually contain the specific cause.
Restart the Flexi server service, or the database if necessary.
⚠️ If the error occurs repeatedly (typically during closing periods or while integrations are running), it is most often caused by an exhausted connection pool or an undersized server. In that case, the solution falls to your server administrator, or to our support team for cloud installations.