Hi @Bikram Pal ,
Thank you for posting in this community.
Here are some potential solutions based on similar issues:
1.Browser Compatibility: Sometimes, browser compatibility can cause issues. Try using a different browser.
2.Verify if the document library has the "Require documents to be checked out before they can be edited" option enabled. If so, users must check in the documents before they can be uploaded.
3.File Explorer Upload: You can try uploading the files using File Explorer. Open the SharePoint library in File Explorer (Windows Explorer), navigate to the folder where you want to upload the new version of the document, and drag and drop the updated document from your local drive into the SharePoint library.
4.Updates and Patches: Make sure that your SharePoint Server 2019 is up to date with the latest cumulative updates and patches. Sometimes, installing the latest updates can resolve these issues.
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