The Z-Ray database was not created successfully. Some common symptoms are a file-size of 0 for /usr/local/zend/var/db/devbar.db. SQL related error messages when visiting the Z-Ray page in the UI (Configurations > Z-Ray). Z-Ray not loading on pages as expected.
Zend Server 7
The Z-Ray database can be regenerated with the following steps, run as root. For some distributions this will require using sudo.
Under certain conditions, the sqlite database used by Z-Ray is not generated correctly. The database must be generated manually.