I have a unique url field in several tabs. If any of the entered urls are not valid and you are not viewing the tab with the invalid url, when the user hits save, nothing happens, i.e., there is no indicator of where the error is located. Now the user has to go into each tab and hit save to find out which field is not valid.
It would be better if the validation was done when the field focus changes, not on save or have save popup an alert box showing all errors when the form is saved.
If you're using the validation, then you're able to set the error message for each field. So, with specific messages, users will know which field has error and will be able to find it in tabs.
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