參考資料

I finally solved it by installing a third-party version of ExtJS from the following url: http://archive.cloudera.com/gplextras/misc/ext-2.2.zip

Then following the steps:

1. Stop Oozie service from Ambari
2. Copy it to the path:
   /usr/hdp/current/oozie-client/libext/
3. Regenerate the war file by executing:

$ /usr/hdp/current/oozie-server/bin/oozie-setup.sh prepare-war

4. Start Oozie again
   Hope it helps!

Step by step instruction:

wget http://archive.cloudera.com/gplextras/misc/ext-2.2.zip

sudo cp ext-2.2.zip /usr/hdp/current/oozie-client/libext/
sudo chown oozie:hadoop /usr/hdp/current/oozie-client/libext/ext-2.2.zip
sudo
 
 -u oozie /usr/hdp/current/oozie-server/bin/oozie-setup.sh prepare-war