WCF service with Full Memory Error (Memory gates checking failed because the free memory) – How to resolve

Try setting minFreeMemoryPercentageToActivateService to 0 in your web.config for WCF Host, as suggested in this answer

<system.serviceModel>
    <serviceHostingEnvironment minFreeMemoryPercentageToActivateService="0"/>
</system.serviceModel>

Edit 1: this provides a workaround but does not address the root cause. Depending on your specific situation this may or may not be good enough.

Edit 2: as correctly pointed out in comment by @radderz “The ‘serviceHostingEnvironment’ element needs to be a child of ‘system.serviceModel'”, see MSDN documentation