If ABRA Flexi is running on Linux and certain operations get stuck — typically saving a contact's password or other encryption-related actions — the cause is usually a lack of entropy ("randomness") on the server.
How to identify it
The amount of available entropy is displayed by:
cat /proc/sys/kernel/random/entropy_avail
The value should be in the thousands. If it's significantly lower and the system is currently hanging on encryption-related operations, this is a strong signal that this is indeed the problem.
ℹ️ The entropy source used depends on the distribution and Java version. It's usually /dev/random, which blocks when there's insufficient randomness — that's why the wait shows up as the application "hanging" rather than as an error.
Solution
The most reliable fix is to add an entropy generator to the system — the rngd daemon from the rng-tools package. On RHEL/CentOS family distributions, it is installed and enabled as follows:
yum -y install rng-tools
systemctl enable --now rngd
On older systems, where rngd runs as a classic service, it also needs to be pointed to /dev/urandom — add the following to the /etc/sysconfig/rngd file:
EXTRAOPTIONS="-r /dev/urandom"
and start the service (service rngd start, chkconfig rngd on). On newer distributions, the daemon is usually already active by default.
⚠️ Make any changes to the server configuration in agreement with your administrator. For cloud-hosted operations, you won't have access to server settings — please contact support, who will check the instance's operation.
💡 If requests are hanging even where encryption isn't involved, the cause is likely different — long-running requests are described in the article REST API returns a timeout.