Consider the following scenario:
You create a .csv file to import a term set into SharePoint Online.
In the SharePoint admin center, you use the term store tool to import the file.
In this scenario, you receive the following error message:
Not all terms were imported successfully. Please see the server log for more information.
To work around this issue, only use the term store tool to import term sets that contain fewer than 5,000 terms. To import large term sets, use the Client Side Object Model (CSOM).
This issue occurs when you try to import more than 5,000 terms by using the term store tool in the SharePoint admin center. This is a known issue in SharePoint Online.
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