After an upgrade, following the steps from 2022.5 to 2023.11 and finally 2024.12, Qlik Compose returns a generic UI error during connection tests.
UI ERROR Unable to connect to the remote server
Reviewing the Qlik Compose server log reveals the Java process is failing to start entirely:
[INFO ] Java Server: . [ERROR] Java Server: Error: Could not create the Java Virtual Machine. [ERROR] Java Server: Error: A fatal exception has occurred. Program will exit. [INFO ] Java Server: <JAVA_HOME>/lib/ext exists, extensions mechanism no longer supported; Use -classpath instead. [WARN ] The Compose java server was restarted. [ERROR] Java Server: Error: Could not create the Java Virtual Machine. [ERROR] Java Server: Error: A fatal exception has occurred. Program will exit.
While the Qlik Compose server is running, the Java agent is down.
The details upgrade path followed was:
2022.5.0.2333 to 2023.11.0.1029, which was successful
2023.11.0.1029 to 2024.12.0.402, which was unsuccessful
Resolution
Stop the Qlik Compose services
Rename or remove the /ext folder in the Compose/java/lib/jre/lib directory
Start the Qlik Compose services
Cause
When the second hop was done, the installation recreated the /ext folder within Compose/java/lib/jre/lib with no files within. As Compose 2024.12 uses Java 17, it doesn’t support ext folder.