You can check here .
[Oct 23 2014 01:15:30.000000 - ERROR] POST /api/adwords/reportdownload/v201406 HTTP/1.1
User-Agent: curl, gzip
Accept: */*
Accept-Encoding: gzip
Authorization: Bearer ya29.pwDtufGnaZv9KHUJkTbXdm6vsMOVrTpsZYCeAvuTqH-h1mZ6nXr3k8ep
developerToken: Token
clientCustomerId: ..8484
Content-Length: 1226
Expect: 100-continue
Content-Type: multipart/form-data; boundary=------------------------e0d01ac807f007e7
Parameters:
__rdxml: <?xml version="1.0"?>
<reportDefinition>
<selector>
<fields>AdFormat</fields>
<fields>AdGroupId</fields>
<fields>AdNetworkType1</fields>
<fields>AdNetworkType2</fields>
<fields>CampaignId</fields>
<fields>CityCriteriaId</fields>
<fields>ClickType</fields>
<fields>CountryCriteriaId</fields>
<fields>CreativeId</fields>
<fields>CriteriaId</fields>
<fields>CriteriaParameters</fields>
<fields>Date</fields>
<fields>Device</fields>
<fields>GclId</fields>
<fields>MetroCriteriaId</fields>
<fields>MonthOfYear</fields>
<fields>Page</fields>
<fields>RegionCriteriaId</fields>
<fields>Slot</fields>
<fields>UserListId</fields>
<dateRange>
<min>20141019</min>
<max>20141019</max>
</dateRange>
</selector>
<reportName>daily clicks performance report #1414048519</reportName>
<reportType>CLICK_PERFORMANCE_REPORT</reportType>
<dateRangeType>CUSTOM_DATE</dateRangeType>
<downloadFormat>CSV</downloadFormat>
<includeZeroImpressions>false</includeZeroImpressions>
</reportDefinition>
Response Code: 500
Error Message: Report download failed. Underlying errors are
Type = 'ReportDownloadError.ERROR_GETTING_RESPONSE_FROM_BACKEND', Trigger = 'Unable to read report data', FieldPath = ''.
Hope I have provided enough information.