Error handling

Power Fx includes a preview feature that enables formula-level error handling. By default, this feature is turned on in Settings.

This setting provides access to formulas like IfError, IsError, Error, and IsBlankorError. These functions allow you to detect errors, provide alternative values, or take specific actions based on the error.

Validation error handling

These functions help validate inputs like incorrect formats or required fields. Use If statements or functions like IsBlank and IsError to validate user input. Provide clear error messages and prevent further processing until the input is corrected.

If( IsBlank(TextInput.Text),
    Notify("Field cannot be blank", 
    NotificationType.Error),
    // Continue with processing
)

Patch function error handling

Similar to the previous example, Error functions help catch errors while patching data to a data source. The Patch function reports errors in two ways.

It can return an error value as the result of the operations.

UpdateContext(
    {   
    result : Patch(
             Feeds,
             Defaults(Feeds),
             {
                 createdon: Now(),
                 crde8_content: TextInput1_1.Text
                 cr9ce_imageurl: filename
             }
        )
    }
)

You can detect errors with IsError and replace or suppress them with IfError.

IfError(result, Notify("There was an issue saving data" , NotificationType.Error));
IfError(result, Notify("There was an issue saving data" , & FirstError.Message, NotificationType.Error))

If(
    IsError(
        Patch(
            Feeds,
            Defaults(Feeds),
            {
                createdon: Now(),
                crde8_content: TextInput1_1.Txt,
                cr9ce_imageurl: filename        
            }
        )
    ),
    Notify("Error: There was an issue saving data", NotificationType.Error)
)

Forms error handling

When you use Forms to submit data with the SubmitForm function, use the Form control property OnFailure to notify users of error messages.

// OnSelect property of the form's submit button
SubmitForm(frm_SubmitData);

// OnSuccess property of the form
Navigate('Success Screen');

// OnFailure property of the form
Notify("Error: the invoice could not be created", NotificationType.Error);

Custom error message with OnError property

The Power Apps OnError property lets you capture all unhandled errors in your app. The OnError property gives you the ability to execute an expression that runs every time an error isn't handled by the app (such as storing it in a variable or using a function such as IfError to replace it with some other value). To use the OnError property, you need to add it to the app that you want to apply it to. Then, you can specify the error message that you want to display by writing a formula in the OnError property box.

It's important to note that App.OnError can't replace the error in the same way that IfError can. At the point that App.OnError is executed, the error has already happened, and the result has propagated through other formulas. App.OnError only controls how the error is reported to the end user and provides a hook for the maker to log the error if desired.

This code on App.OnError can help locate the source of the error:

Notify(
    Concatenate(
        FirstError.Message,
        ", Observed: ",
        FirstError.Observed,
        ", Source: ",
        FirstError.Source
    ),
    NotificationType.Error
)

Related information

Power Fx error handling

Next step

Monitoring and testing