Failed to call the license server API

When running the installable cloud app, the Web API console displays the following error:

2021-01-27 01:28:32,094 ERROR PowerServer.Client.PowerServerClient.LogMessage [0] - MESSAGE: Failed to call the license server Api. 
(Error connecting to A connection attempt failed because the 
connected party did not properly respond after a period of time, or established connection failed because connected host has failed 
to respond..)

Cause & Solution:

First, please note that it is possible that the PowerServer console may output the following error information but the application is still running properly. That is because the system allows a grace period in cases when PowerServer fails to validate the license. After the grace period, PowerServer will stop responding the requests from the application.

The error here indicates that PowerServer cannot connect to However, according to the latest information in PB Help, PowerServer is required to connect to and, or and The cause of the error must be, the PowerServer Runtime version is too old. You shall manually update the PowerServer.Core and PowerServer.Api NuGet packages to the latest version.