Error messages with severity level 18 indicate an internal software bug. However, the command runs to completion, and the connection to Adaptive Server is maintained. The user can continue with the work they are doing, although they may not be able to execute a particular command. An example of a situation that generates severity level 18 is Adaptive Server detecting that a decision about the access path for a particular query has been made without a valid reason.
Since problems that generate such messages do not keep users from their work, users tend not to report them. However, users should be instructed to inform the system administrator every time an error message with this severity level (or higher) occurs so that the system administrator can report them.
