I've had this problem over the last few days where I can only access the first page of any search results. As soon as I click the next button or any page number I get the Error 400 screen.
This is using Safari 9.1.1 on Yosemite 10.10.5
The Adobe Stock team is working on a solution for this issue until then please follow the steps in this workaround: Error 400 Workaround
However, this only works once. Not really practical to clear cache and restart browser for each page of results.
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