Magento :: Product image upload broken after upgrade or SUPEE-8788

Note: This is a historical reference, not a current security baseline. Magento 1 is end-of-life.

Problem description

After Magento upgrade to 1.9.3 or installation of SUPEE-8788 patch image upload is broken at Catalog > Manage Products > Product details > Images tab. It is not possible to upload new images, or Upload button is missing.

Cause and solution

See SyntaxError: expected expression, got ‘,’ for details.

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