With a chance of about 20-30% a mongodump of a replicaset Secondary will fail with the message:

"2015-09-08T02:24:48.188+0200 Failed: error reading collection: invalid cursor".

Every backup is done locally with the following command:

C:\Server\MongoDB3\bin\mongodump.exe --port XXXXX --host server.url --out OutputDir --ssl --sslPEMKeyFile "C:/Server/SSL/server.url.pem" --sslCAFile "C:/Server/SSL/ca.pem"

The server log: (there are 7 dumps running at that moment, 1 seems towork, the other 6 fail)
2015-09-08T02:24:50.311+0200 I QUERY [conn36370] getmore 2GCAccounting.Entry cursorid:70099837830 ntoreturn:0 keyUpdates:0 writeConflicts:0 numYields:53 nreturned:4237 reslen:4195200 locks:{ Global: { acquireCount:

}, Database: { acquireCount:

}, Collection: { acquireCount:

} } 950ms
2015-09-08T02:24:53.454+0200 I NETWORK [conn36366] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49573]
2015-09-08T02:24:53.454+0200 I NETWORK [conn36365] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49565]
2015-09-08T02:24:53.650+0200 I NETWORK [conn36368] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49583]
2015-09-08T02:24:53.650+0200 I NETWORK [conn36369] end connection 10.13.15.10:49585 (11 connections now open)
2015-09-08T02:24:53.651+0200 I NETWORK [conn36367] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49584]
2015-09-08T02:24:53.651+0200 I NETWORK [conn36370] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49586]
2015-09-08T02:24:53.651+0200 I NETWORK [conn36372] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [10.13.15.10:49589]