Manual:$wgDisableUploads

Files and file uploads: $wgDisableUploads
Determines whether file uploads are allowed.
Introduced in version:Before 1.1.0
Removed in version:1.5.0
Allowed values:(boolean)
Default value:true

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If set, disables the upload page and hides the link. Note that downloads have to be set up correctly in order to be secure, so this setting allows you to disable the feature if you are worried about security.

Since v1.5.0 $wgDisableUploads has been deprecated in favour of $wgEnableUploads .