Timestamps for API requests are valid for 15 minutes. This error usually occurs when the time of the server creating the request is out of date. Please check if the time of your server is correct and if the time in the error message corresponds to the time the request was created.
Example API Request URL:
http://ecs.amazonaws.co.uk/onca/xml
&Version=2013-08-01&AssociateTag=…
&ItemId=B01J41LRF2&Operation=ItemLookup&ResponseGroup=ItemAttributes,…
&Timestamp=2018-06-24T17:24:11.000Z&Signature=zyZjNTQaDd9Ok…