Error handling

Power Fx supports formula-level error handling. This feature is turned on by default for all new apps. However, some older apps might have it turned off in app Settings. We recommend keeping this feature turned on.

To check if this feature is turned on:

1. Open a canvas app for editing.
2. Go to the Settings > Updates > Retired tab.
3. Make sure Disable formula-level management is turned off.

When this setting is enabled, you can use formulas like IfError, IsError, Error, and IsBlankorError. These functions help you detect errors, provide alternative values, or take specific actions based on the error. When you turn on this setting, you can write null or blank values to data sources. When you turn off this feature, errors are returned as blank values.

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 by using IsError and replace or suppress them by using 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 by using 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 by using the OnError property

The Power Apps OnError property captures all unhandled errors in your app. By using the OnError property, you can run an expression every time the app encounters an unhandled error. For example, you can store the error in a variable or use a function like IfError to replace the error with another value. To use the OnError property, add it to the app where you want to handle errors. Then, write a formula in the OnError property box to specify the error message you want to display.

App.OnError can't replace the error like IfError can. When App.OnError runs, the error already happened and the result already went through other formulas. App.OnError only controls how the error is reported to the end user. It also provides a way for the maker to log the error if they want.

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

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