The file name was S-54010 VAOM-4701 DM_flex def_09072022.xlsx. I changed it to S-54010 VAOM-4701 DM_flex def_09222022.xlsx and it uploaded. I still can't upload a file with the original name. I do not see any other files with that same name on the page (it is not a very big page).
From the error message, your Confluence instance has Cenote Lockpoint installed to protect attachments from editing, and that message comes from our app.
If an attachment of the same name exists on the page, you would need to navigate to the "... → Attachments" page, find that similar attachment, then select the "Lock" link next to the attachment name, which would then allow it to be edited.
As Lockpoint is currently configured on your system, it requires the attachment to be locked before any sort of modification would be permitted. Alternatively, Lockpoint also supports a "Smart Locking" mode in which it only prevents attachments from being modified if they are already locked by another user. Switching to this mode would allow you to edit the attachment without going through extra steps. This option would need to be enabled by your Confluence Administration on the global Lockpoint configuration page.
From some of the earlier comments, it seems like you might be saying that the file does not already exist on the page. In this case, the locking message is unexpected. If you can verify through the Attachments page that the file does not actually exist, we would love to look into this further. (Note that you cannot necessarily rely on the Attachments macro to show you full data, since the macro may be configured to filter out some of the attachments on the page, which is why the best place to verify is on the Attachments page using the instruction suggested above.)
In any event, if the problem still persists, you can contact us directly on our support site to open a ticket, and we will be happy to investigate further.
Scott @ Cenote
It's an Excel file. I can't take a screen print, but this is the error I get when I try to insert the file:
I don't know how to inspect permissions, but since I have successfully uploaded other files to this page, I doubt that's the problem.