Guides
How to Find All Invalid Entries in Google Sheets at Once
Google Sheets flags a cell that breaks a validation rule with a red triangle, but it never gives you a list of them, and on a workbook with many tabs the invalid entries hide in plain sight. How to list every invalid cell across all tabs with a helper formula, a conditional formatting highlight, an Apps Script that uses Google's own validity check, or one click in a sidebar.
How to Copy a Dropdown or Data Validation Rule to Another Spreadsheet Without Breaking It
Paste a dropdown into another Google Sheets file and it often arrives empty, because a dropdown from a range still points at a list that only exists in the original file. Which rule types copy cleanly, how to bring the list along and re-link or convert the rule, and how to move a whole set of rules between files as JSON.
How to Update a Dropdown List Used on Many Tabs in One Go
When the same dropdown sits on a dozen tabs, adding one option means editing a dozen rules, and the tabs drift apart as soon as one is missed. How to make every tab read one list range, how to paste or script an edited rule onto all tabs, and how to propagate one edited cell's rule to every tab that carries the old one.