As far as I know there is no standard for messages of this kind.
I would expect that "normal" language is the best way to express yourself to a user. So it would be something like "Please enter your first name."
If it's an error message because a user did not enter a first name, it could even be something like: "You forgot to enter your first name in this field. Would you be so kind to fill in your first name?"
It depends on the software and the user profile. If the software is for technicians and super-users / developers something like this will do: "First name is Mandatory."
1. Provide “Next Steps for users” to guide them with the problem.
E.g. If the error is non recoverable and the only way to work around it is to restart the browser-Provide a Logout button and some verbiage describing the problem and the solution.
The following error occurred while <describe action taken>:
<error details> or <exception text> or < something meaningful>
Ideally, we recommend using information on how to recover - possibly even just the standard "Please contact your system administrator."
2. Provide some informative message about the next steps after the error has occurred.
E.g. “You may have to log out and log back in”
Consider using a LOGOUT button on the modal windows for critical errors.
3. Consider providing the technical support # or email address in the error message.
4. Consider providing an Error List page or a dialog that would return a list of all the errors found. This will be useful as the user will be able to find all errors occurred.
5. When writing error messages follow these basic rules:
• Be constructive
• Be precise
• Speak the users’ language
• Be polite (for example, avoid words like “not valid”, “error” or “illegal operation”, etc)
• Do not violate business or security constraints (example: “User name not valid” or “User name valid, but password does not match”)
The right way is to use the language which is easily understand by the user. Because we are displaying the message for user only.
It must be concise and meaningful, where the actual problem lies or what user has forgotten to enter.