4.5.3: An error occurred in the upload. Please try again later.

Shortly after I was automatically upgraded to 4.5.3 WordPress started doing this on my server.

You can upload a small test JPG anywhere using the media uploader and it fails with an error message reply.
“An error occurred in the upload. Please try again later.”

Screenshot Link

Using FTP (or a Media/Page reload) I can confirm that the actual upload is performed and the necessary thumbnails are being generated correctly.

I have already tested that disabling all plugins doesn’t solve the issue.

Here is the output of the browser’s async-upload.php:

{"success":true,"data":{"id":3040,"title":"test-file-1","filename":"test-file-1-1.jpeg","url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1.jpeg","link":"http:\/\/www.brandbrilliance.co.za\/test-file-1-2\/","alt":"","author":"4","description":"","caption":"","name":"test-file-1-2","status":"inherit","uploadedTo":0,"date":1.467892618e+12,"modified":1.467892618e+12,"menuOrder":0,"mime":"image\/jpeg","type":"image","subtype":"jpeg","icon":"http:\/\/www.brandbrilliance.co.za\/wp-includes\/images\/media\/default.png","dateFormatted":"July 7, 2016","nonces":{"update":"213656b981","delete":"09e07694d8","edit":"c864aa7382"},"editLink":"http:\/\/www.brandbrilliance.co.za\/wp-admin\/post.php?post=3040&action=edit","meta":false,"authorName":"John Brand","filesizeInBytes":138811,"filesizeHumanReadable":"136 kB","sizes":{"thumbnail":{"height":150,"width":150,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-150x150.jpeg","orientation":"landscape"},"medium":{"height":200,"width":300,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-600x400.jpeg","orientation":"landscape"},"fixedslideshow":{"height":540,"width":600,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-600x540.jpeg","orientation":"landscape"},"full":{"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1.jpeg","height":600,"width":600,"orientation":"landscape"},"post-thumbnail":{"height":56,"width":56,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-56x56.jpeg","orientation":"landscape"},"tinyfeatured":{"height":75,"width":75,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-75x75.jpeg","orientation":"landscape"},"gallery":{"height":351,"width":426,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-426x351.jpeg","orientation":"landscape"},"fullslideshow":{"height":600,"width":600,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-600x600.jpeg","orientation":"landscape"},"slim":{"height":210,"width":420,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-420x210.jpeg","orientation":"landscape"},"square":{"height":425,"width":420,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-420x425.jpeg","orientation":"portrait"},"big":{"height":598,"width":600,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-600x598.jpeg","orientation":"landscape"},"blogonecol":{"height":325,"width":575,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-575x325.jpeg","orientation":"landscape"},"blog":{"height":215,"width":420,"url":"http:\/\/www.brandbrilliance.co.za\/wp-content\/uploads\/2016\/07\/test-file-1-1-420x215.jpeg","orientation":"landscape"}},"height":600,"width":600,"orientation":"landscape","compat":{"item":"<input type=\"hidden\" name=\"attachments[3040][menu_order]\" value=\"0\" \/><p class=\"media-types media-types-required-info\">Required fields are marked <span class=\"required\">*<\/span><\/p>\n\t\t\t<table class=\"compat-attachment-fields\">\t\t<tr class='compat-field-media_category'>\t\t\t<th scope='row' class='label'><label for='attachments-3040-media_category'><span class='alignleft'>Media Categories<\/span><br class='clear' \/><\/label><\/th>\n\t\t\t<td class='field'><ul class=\"term-list\">\n<li id='media_category-99' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][99]' \/><input value='1' type='checkbox' name='tax_input[media_category][99]' id='in-media_category-99' \/>About<\/label><\/li>\n\n<li id='media_category-97' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][97]' \/><input value='1' type='checkbox' name='tax_input[media_category][97]' id='in-media_category-97' \/>Blog<\/label><\/li>\n\n<li id='media_category-125' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][125]' \/><input value='1' type='checkbox' name='tax_input[media_category][125]' id='in-media_category-125' \/>Brief<\/label><\/li>\n\n<li id='media_category-102' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][102]' \/><input value='1' type='checkbox' name='tax_input[media_category][102]' id='in-media_category-102' \/>Headers<\/label><\/li>\n\n<li id='media_category-103' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][103]' \/><input value='1' type='checkbox' name='tax_input[media_category][103]' id='in-media_category-103' \/>Home<\/label><\/li>\n\n<li id='media_category-101' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][101]' \/><input value='1' type='checkbox' name='tax_input[media_category][101]' id='in-media_category-101' \/>Logos<\/label><\/li>\n\n<li id='media_category-98' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][98]' \/><input value='1' type='checkbox' name='tax_input[media_category][98]' id='in-media_category-98' \/>Portfolio<\/label><\/li>\n\n<li id='media_category-118'><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][118]' \/><input value='1' type='checkbox' name='tax_input[media_category][118]' id='in-media_category-118' \/>Previews<\/label><\/li>\n\n<li id='media_category-119' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][119]' \/><input value='1' type='checkbox' name='tax_input[media_category][119]' id='in-media_category-119' \/>Scrapbook<\/label><\/li>\n\n<li id='media_category-100' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][100]' \/><input value='1' type='checkbox' name='tax_input[media_category][100]' id='in-media_category-100' \/>Services<\/label><\/li>\n\n<li id='media_category-96' class=\"popular-category\"><label class='selectit'><input value='0' type='hidden' name='tax_input[media_category][96]' \/><input value='1' type='checkbox' name='tax_input[media_category][96]' id='in-media_category-96' \/>Site<\/label><\/li>\n<\/ul><\/td>\n\t\t<\/tr>\n<\/table>","meta":""},"filesize":"136 kB","taxonomies":{"media_category":[]}}}<!DOCTYPE html>
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