Common Errors and Troubleshooting in Programming
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A label's formula uses a variable, and Power Apps underlines it in red: Name isn't valid. 'locMember' isn't recognized. The name is spelled correctly. The variable simply doesn't exist yet, because nothing in the app creates it.
Patch fails with Network error when using Patch function: [YourList] ETAG mismatch. It isn't a network problem. The SharePoint item changed after your app read it, so SharePoint refused to overwrite the newer version. Catch it with IfError, tell the person what happened, and reload the item.
You rename a control in Tree view, and Power Apps stops you: Can't rename. This name is already being used. Please try a different name. Another control in the app already has that name, possibly on a different screen.
A control gets a red error icon, and its details say Unexpected characters. Characters are used in the formula in an unexpected way. Power Apps found a character it can't place in one of the control's formulas. In the example it was one closing bracket too many.
A gallery's OnSelect passes the selected row to another screen, and Power Apps marks it as an error: Incompatible type. We can't evaluate your formula because the context variable types are incompatible with the types of values in other places in your app. In the example, Self.Selected caused it, and ThisItem fixed it.
Focus isn't showing in the App checker means a control's focus border has a thickness of 0. Someone moving through the app with the keyboard can't see when they've landed on it. For anything they can tab to, give it a border; for a control they can't tab to, the border never appears anyway.
The App checker lists Missing tab stop under Accessibility errors: a control it considers interactive has no place in the keyboard's Tab order. For a gallery, the fix is TabIndex 0. For a plain heading, Microsoft's guidance points the other way, so think before you change it.
You want a badge's color to follow its text, so you write Switch(Self.Content, ...) in its Intent. Studio underlines Content and says Name isn't valid. 'Content' isn't recognized. The modern Badge's text can't be read that way. Base the color on the same value the text comes from.
You set a label in a gallery to a SharePoint column, and instead of text you get a red error icon and Expected Text value. The column is a Choice column, and Power Apps gets a Choice as a record, not as text. Add .Value and it works.
The App checker in Power Apps Studio lists red errors: Missing accessible label, one per control. Your screen looks fine, but people using a screen reader get nothing useful from those controls. The fix is to give each one an AccessibleLabel that says what it is or what it does.
