For further troubleshooting the issue, could you please give me some detailed instructions?
1.What is the version of your SharePoint? SharePoint online or SharePoint server?
2.What exactly operation did you do when getting the error? Just open the folder?
3.Which error did you got when loading the folder? Please attach the attachment.
4.Whether you occur the error when opening other folders?
Clear the browser or in the incognito mode to open the folder.
If you use the modern experience, return to the classic experience, then try to open the folder.
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