Describes the cause and action for error messages.
Error Message(English)：
dropdown in excel is not working
Drop Down List Opens With ...
https://www.contextures.com/xlDataVal08.html#blankcell
Data Validation Dropdowns ...
https://www.contextures.com/xlDataVal08.html#Change
Missing Arrows
https://www.contextures.com/xlDataVal08.html#ArrowsNotVisible
Problem Solved: Dependent Drop Down Lists in Excel - YouTube
https://www.youtube.com/watch?v=aidOWOsMdD8
https://www.youtube.com/watch?v=aidOWOsMdD8
Drop down menus not working in all spreadsheets : excel - Reddit
https://www.reddit.com/r/excel/comments/2s8764/drop_down_menus_not_working_in_all_spreadsheets/
Video: Drop-down list settings - Excel - Microsoft Office Support
https://support.office.com/en-ie/article/video-drop-down-list-settings-76a28e61-eeda-4577-a79d-2fdb8・・・
Excel 2013 drop-down menu not visible in Excel 2007 - Microsoft
https://social.technet.microsoft.com/Forums/lync/en-US/0ca479fb-ebda-4fea-a2cf-1e9e8cd8c811/excel-20・・・
Excel 2010 Drop-Down disappears when file is saved/reopened ...
https://answers.microsoft.com/en-us/msoffice/forum/all/excel-2010-drop-down-disappears-when-file-is/・・・