Suddenly we started getting above error in one of our MS CRM Dev environment where we have one WCF Rest service running for MS CRM 2013 custom integration. After enabling tracing in wcf service we found below detailed error message
<Message>Memory gates checking failed because the free memory (175853568 bytes) is less than 5% of total memory. As a result, the service will not be available for incoming requests. To resolve this, either reduce the load on the machine or adjust the value of minFreeMemoryPercentageToActivateService on the serviceHostingEnvironment config element .</Message>
After adding below line in web config, this issue got resolved.
<serviceHostingEnvironment minFreeMemoryPercentageToActivateService=”0″ />