Problem uploading using S3 file upload

Thanks for your continuing help with this. If I have a file using the Single option, it works fine. If I change Single to Double - and make no other changes - the signature not matching error appears. There is also a ‘Cors Missing Allow Origin’ error. Doesn’t this mean neither the api key nor expire time can be the problem? ie:

With this setting it works:

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If I simply change this (ie same server action etc), it fails:

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Is there something I’m missing? Is there something I should be changing in the api/server action file? You mentioned increasing the expire time and I changed this:

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Is that what you meant? (It didn’t seem to make any difference.)