If a Formula Field is misconfigured in some way it will display an error message.
There are two types of error message displayed - one for the Solution Manager during formula configuration, and one for end users who are trying to view data and have an erroring Formula Field displayed.
Common things that break formulas:
Changes to Field properties (especially changing field type!)
Removing or modifying Linked Records
End User Error Message
If a formula is producing an error, end users will see the following display in grid view:
Solution Managers can click on the (i) icon to edit the formula and fix the error.
Formula Builder Error Messages
The following error messages are displayed to the Solution Manager in the Formula Builder interface. The red error message will be displayed in the lower left side of the formula entry box, as shown below:
The most commonly displayed error message is Invalid Syntax, indicating that there is something structurally wrong with the current formula. You might be missing a closing parenthesis, have mistyped a field name or have forgotten a function parameter.
If you have an error in a function's input you'll get a "not defined" message as an error. This indicates that the system doesn't understand the input - did you forget to put square brackets around a field name?
Type Not Allowed
This error is generated if you try to use an incompatible type as an argument to a function. For example, trying to SUM a Member Field produces this error:
This error will also be generated if you try to use a list of values as a single value (the error will say "with type 'list of [Field]' NOT allowed")
Function Not Defined
If you have a typo in a function's name (or that function is not yet implemented), a function "NOT defined" error will be returned.
Min Args Count
If you do not provide all of the required arguments to a function it will return an error in the following format:
[FUNCTION NAME]: MIN args COUNT is [number]
Incompatible Field Types
Building an expression that mixes incompatible field types will produce the following error message:
[FUNCTION NAME]: [Field 1] AND [Field 2] cannot participate in an expression together.