Your WordPress installation has a problem with outputting extra white space
Outputting extra white space – Your WordPress installation has a problem with outputting extra whitespace. This can corrupt backups that you download from here. Follow this link for more information
If UpdraftPlus has warned you about extra white space, then this page explains the meaning of this warning. N.B. This problem does not affect the backing up process or the integrity of your backups. It only affects downloading your backups using the UpdraftPlus dashboard page, and can be worked around; please read on!
Some plugins or changes that you make to WordPress can cause extra spaces and/or line feeds (return characters) to be added to the output of every WordPress page. This is not usually a problem since they are invisible.
Fix Outputting Extra White Space
However, this is a problem when data other than text is being sent – e.g. when you are downloading a backup file from the UpdraftPlus console. Here, extra characters can change and corrupt the file. For example, if you add extra spaces into a zip archive, then it cannot be opened until they are removed again.
Firstly, if you are having this problem, then you may be able to directly download your backup files via FTP (i.e. instead of downloading them via the WordPress dashboard). This will circumvent the problem. After downloading from cloud storage to your web server within the UpdraftPlus page, then instead of downloading from there to your computer, instead just log into your FTP account, and look in wp-content/updraft (or, if you changed the default, wherever you configured to store your backups).
If you can, it is best to find and fix the problem. It is most likely to be in one of your plugins. You should de-activate them all (except UpdraftPlus, of course), and then re-load the UpdraftPlus page, and see if the problem has gone away. Assuming that it does, you can then re-activate the plugins one-by-one, and find out which one causes the error to return. You can then report the problem to the plugin author.
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If the problem is in none of your plugins, then it must be in some other part of your WordPress install, that has been modified from the default. Hunting it down can be frustrating – but it’s in there somewhere… you could also temporarily switch theme to a default theme (e.g. TwentyTwelve, TwentyThirteen). If that doesn’t find it, then try checking your wp-config.php file.
The issue is most likely caused by excessive blank lines at the beginning or end of (at least) one of the PHP scripts in the Theme’s code. The additional lines are appended to any output when these scripts are loaded.
You can retrieve your backups straight from remote storage in the meanwhile. Extra whitespace generally only impacts UpdraftPlus’s ability to download backup files.
How to fix outputting extra white space in WordPress
If UpdraftPlus has issued a warning regarding excessive white-space, this page explains what that warning means. Note that this issue has no bearing on the backup procedure or the integrity of your backups. It only affects backup downloads via the UpdraftPlus dashboard page, and it can be worked around; please continue reading!
Extra spaces and/or line feeds (return characters) may be added to the output of every WordPress page if you use certain plugins or make changes to WordPress. Because they are invisible, this is typically not a concern.
When data other than text is provided, such as when downloading a backup file from the UpdraftPlus dashboard, this becomes a problem. Extra characters can modify the file and cause it to be corrupted. If you add additional spaces to a zip archive, for example, you won’t be able to access it until you remove them.
To begin, if you are experiencing this issue, you may be able to retrieve your backup files directly using FTP (i.e. instead of downloading them via the WordPress dashboard). This will get around the issue. After downloading from cloud storage to your web server using the UpdraftPlus website, instead of downloading to your machine, connect into your FTP account and check under the wp-content/updraft folder (or, if you changed the default, wherever you configured to store your backups).
It is preferable to locate and resolve the issue if at all possible. It’s almost certainly in one of your plugins. Deactivate all of them (excluding UpdraftPlus, of course), then reload the UpdraftPlus page to check whether the problem has gone away. If it does, you may reactivate the plugins one by one to see which one is causing the issue to reappear.