Upgrading from version 2.8.4 to 3.3.1

You would not be able to do so until you reinstalled them. Lots of people would not delete these, they would just ftp the new files over the old ones.

Make sure you do a backup before proceeding it.

Hi Helen-kh,

There is no need to delete files first and then upload the new ones. I would recommend you to simply download each version from the Release Archives, extract them and start uploading starting from the oldest to the newest.

There is no need to upload wp-config-sample.php and make sure you never overwrite wp-config.php.

There is no need to delete files first and then upload the new ones.

I disagree. The recommended procedure is to delete the old files & folders before uploading the new versions.

Hi esmi,

Thank you for the tip. Is there any reason why? Could it be just in case some files are being obsolete between versions?

Not so much obsolescence as ensuring that you really do update every single file. Sometimes – especially when doing a bulk overwrite – an odd file can get missed. A delete followed by an upload means that a missed file will be just that – missing – as opposed to not being upgraded. The site should fall over immediately with a fairly clear error. In comparison, a site with 1 or 2 old files on it can start to behave unpredictably – making it difficult to pin down the cause.

@esmi

Very good point indeed ?? Though I tend to check the FTP client queue also and keep an eye on the missed uploads. Good method though.

Thanks all for your tips ??
I still have the question on login ability if I replace the admin folder.
Also after replacing the files and folders, do I prompt to another installation process, or is it bypassed?

Another thing I wonder: what happens if I install the very newest version from the start and then use the old config.php and wp-content folder to overwrite the old ones? Why does it have to be incremental?

As all suggested you should be safe by doing the following:

1. Download the next available build of WordPress.
2. Copy the wp-config.php details from your live server to the offline files (mainly db name, username, password and host).
3. Delete all files.
4. Upload the new files.
5. Once uploaded navigate to https://[yourwebsite]/wp-admin/upgrade.php.

If there is a need for you to login, WordPress will prompt you for it and yes you will still be able to login since the latest files have been already uploaded.

Repeat the above process for each build of WordPress.