Since the update servers no longer exist, the most permanent fix is to stop the IDE from looking for patches altogether. Open your Flex Builder 3 / Flash Builder IDE.
If the IDE is stuck in a loop trying to read a broken patch list, clearing the local cache files will force it to reset. Close your IDE completely. Navigate to your workspace directory. Locate the hidden .metadata folder. Inside .metadata , go to .plugins . patch listing error flex 3
The Apache Flex SDK installer is notoriously sensitive to Java versions. Java 11+ breaks the patch listing parser. Since the update servers no longer exist, the
Follow these systematic troubleshooting steps to resolve the patch listing error: Close your IDE completely
: If you are using an older version of Flex 3 or Flex 3 Beta, it may no longer be compatible with current server protocols.