Thank you for posting on our community.
I understand that while navigating to CM > Administration > Alerts, you are getting following error:
A server error has occurred. Send the following information to Cloudera.
Version: Cloudera Express 5.10.0 (#85 built by jenkins on 20170120-1038 git: aa0b5cd5eceaefe2f971c13ab657020d96bb842a)
at AlertData.java line 127
in com.cloudera.server.web.cmf.AlertData isParamSpecEnabled()
-- Above is a known issue and fixed in CM 5.12 which is yet to release. we are also plaining the fix this in upcoming bug-fix release CM 5.10.2
-- As a work around you can visit individual services and set up alerts. For eg., you wanted to enable alert for HDFS then go to CM > HDFS > Monitoring (under CATEGORY filter) and configure/modify appropriate alerts configurations.