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You have written something invalid into one of your forms.
1) Navigate to the erroneous form. You should see red error bars at the top. Take a look at the first error bar on the page for information that could help you identify the error.
2) Open your form in Vellum (the form designer) and fix any errors Vellum identifies. If your form will not display in Vellum, go to the “advanced” dropdown and click “Edit Source XML”.
3) If you still have not identified the error, go to “Edit Source XML” and copy all the content. Paste it into https://www.commcarehq.org/formtranslate/# . Click “verify” to help identify xml errors.
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