When you view a SharePoint Online list in Office 365 Enterprise, you receive the following error message:
The number of items in this list exceeds the list view threshold, which is 5000 items. Tasks that cause excessive server load (such as those involving all list items) are currently prohibited.
To work around this issue, split the items into multiple lists so that no list exceeds 5,000 items. Because you'll be unable to view the list items beyond the limit of 5,000 items, you must configure metadata-based navigation so that you can access all the list's contents.
To enable metadata-based navigation, follow the "Enable Metadata Navigation and Filtering" and "Configure Metadata Navigation" sections of the following Microsoft website:
After metadata navigation is enabled, the list's contents will become available. We recommended that you then reduce the list's contents to less than 5,000 items.
This issue occurs because SharePoint Online uses the Large List Resource Throttling feature. By default, the list view threshold is configured at 5,000 items. When the defined item limit in a list is exceeded, the message is displayed.
For more information about how to manage lists and libraries that contain many items, go to the following Microsoft website: