Quick answer
Most WordPress sites file uploads by year and month. So if you upload a corrected version of a PDF that has been sitting in /uploads/2025/05/ since last year, it does not go back there — it lands in this month’s folder, at a completely different address.
If you need the existing links to keep working, you need a replacement rather than an upload: change the file behind the existing document, and leave the path where it is.
A file that has lived at /uploads/2025/05/ needs to stay at /uploads/2025/05/ even when you are replacing it in September 2026.
Why WordPress does this
Most sites have the setting that organises uploads into year and month folders turned on, so a new upload goes into something like:
/wp-content/uploads/2026/09/
That is genuinely useful for keeping a large media library manageable over the years.
It is also why “just upload the corrected PDF again” gives you a different URL.
Uploading and replacing are not the same thing
Uploading treats the file as new media. You get this year’s folder, a new entry in the Media Library, possibly a -1 on the filename, and every existing link still pointing at the old file.
Replacing keeps the document where it is and changes the file underneath. That is the one you want when the old URL has to keep working.
A real example
A city uploaded:
/wp-content/uploads/2025/05/building-permit.pdf
Residents have it bookmarked. Google has it indexed. It is printed on an instruction sheet at the planning counter.
A correction is made in September 2026. Somebody uploads building-permit.pdf the normal way, and WordPress stores it as:
/wp-content/uploads/2026/09/building-permit.pdf
or possibly building-permit-1.pdf.
Every one of those existing links still serves the old permit form, and nothing about the Media Library suggests a problem.
Why FTP looks like the obvious fix
A developer can overwrite wp-content/uploads/2025/05/building-permit.pdf directly over SFTP, and the URL is preserved.
For one file you know the path of, that is a perfectly reasonable thing to do.
It does skip everything else: nobody reviewed where the file was going, nothing checked whether other pages use it, there is no backup tied to that change, nothing recorded that it happened, and undo means you remembering where you put the original.
Whether that matters depends on how many files there are and who else needs to know.
Does the upload date need to change?
Usually not.
The Media Library entry and the document’s revision are two different things. If the page means “the current file”, the entry can happily stay as it is while its contents change.
Changing the date just to make the record look fresher is not worth doing unless something on your site actually depends on it.
Caching
An old year/month URL has probably been cached for a very long time.
After replacing: open the direct URL, confirm the new content, check your CDN, check your browser, and purge that one file if you need to.
An old folder in the path does not mean the file in it is old.
FAQ
Can I turn off the year/month folders?
Yes, that setting is configurable. But changing it for the whole site is a different question from keeping one existing URL working.
Will uploading the same filename put it back in the old folder?
No. A normal upload is still a new upload, and it goes where new uploads go.
Why did it add -1 as well?
Because a file with that name already existed where it was trying to put it. See the article on that for the details.
Is an old folder path bad for SEO?
No. What matters is that the URL is stable, reachable and serves the right document. The date in the path has nothing to do with how current the file is.
Could I just redirect the old URL to the new one?
You could, if moving the file is acceptable. It is a different approach from keeping the original address, and it means every one of those links takes an extra hop forever.
Summary
Date-based upload folders are one of the main reasons re-uploading a file gives you a new address instead of an updated one.
If what you need is “keep this exact link working”, you need replacement, not an upload.
Related: Why WordPress adds -1 to filenames · Replacement vs FTP · Replace PDF without breaking links