How did you build it? I'm on Ubuntu and used:
make -f makefile.unix USE_UPNP=1 bitcoind
Or are you building the GUI? I haven't tried that. I'll look into it.
No GUI just the daemon and a fresh source tree results in the same error, 64bit system if that makes difference.
miner2@miner2:~/src/doublec-i0coin-6fef194/src$ make -f makefile.unix USE_UPNP=1 i0coind
/bin/sh ../share/genbuild.sh obj/build.h
fatal: Not a git repository (or any of the parent directories): .git
g++ -pthread -Wall -Wextra -Wno-sign-compare -Wno-invalid-offsetof -Wno-unused-parameter -Wformat -Wformat-security -g -DBOOST_SPIRIT_THREADSAFE -I/home/miner2/src/doublec-i0coin-6fef194/src -I/home/miner2/src/doublec-i0coin-6fef194/src/obj -DUSE_UPNP=1 -DHAVE_BUILD_INFO -fno-stack-protector -fstack-protector-all -Wstack-protector -Wl,-z,relro -Wl,-z,now -D_FORTIFY_SOURCE=2 -O2 -o i0coind obj/auxpow.o obj/version.o obj/checkpoints.o obj/netbase.o obj/addrman.o obj/crypter.o obj/key.o obj/db.o obj/init.o obj/irc.o obj/keystore.o obj/main.o obj/net.o obj/protocol.o obj/bitcoinrpc.o obj/rpcdump.o obj/script.o obj/util.o obj/wallet.o obj/walletdb.o obj/noui.o -Wl,-Bdynamic -l boost_system -l boost_filesystem -l boost_program_options -l boost_thread -l db_cxx -l ssl -l crypto -l miniupnpc -Wl,-Bdynamic -l z -l dl -l pthread
obj/db.o: In function `Unserialize':
/home/miner2/src/doublec-i0coin-6fef194/src/main.h:1242: undefined reference to `int ReadWriteAuxPow(CDataStream&, boost::shared_ptr&, int, int, CSerActionUnserialize)'
obj/db.o: In function `Serialize':
/home/miner2/src/doublec-i0coin-6fef194/src/main.h:1242: undefined reference to `int ReadWriteAuxPow(CDataStream&, boost::shared_ptr const&, int, int, CSerActionSerialize)'
collect2: ld returned 1 exit status
make: *** [i0coind] Error 1
miner2@miner2:~/src/doublec-i0coin-6fef194/src$ make -f makefile.unix USE_UPNP=1 bitcoind
make: *** No rule to make target `bitcoind'. Stop.
Oh and if you leave out the upnp you get extra errors.
miner2@miner2:~/src/doublec-i0coin-6fef194/src$ make -f makefile.unix USE_UPNP= i0coind
/bin/sh ../share/genbuild.sh obj/build.h
fatal: Not a git repository (or any of the parent directories): .git
g++ -pthread -Wall -Wextra -Wno-sign-compare -Wno-invalid-offsetof -Wno-unused-parameter -Wformat -Wformat-security -g -DBOOST_SPIRIT_THREADSAFE -I/home/miner2/src/doublec-i0coin-6fef194/src -I/home/miner2/src/doublec-i0coin-6fef194/src/obj -DHAVE_BUILD_INFO -fno-stack-protector -fstack-protector-all -Wstack-protector -Wl,-z,relro -Wl,-z,now -D_FORTIFY_SOURCE=2 -O2 -o i0coind obj/auxpow.o obj/version.o obj/checkpoints.o obj/netbase.o obj/addrman.o obj/crypter.o obj/key.o obj/db.o obj/init.o obj/irc.o obj/keystore.o obj/main.o obj/net.o obj/protocol.o obj/bitcoinrpc.o obj/rpcdump.o obj/script.o obj/util.o obj/wallet.o obj/walletdb.o obj/noui.o -Wl,-Bdynamic -l boost_system -l boost_filesystem -l boost_program_options -l boost_thread -l db_cxx -l ssl -l crypto -Wl,-Bdynamic -l z -l dl -l pthread
obj/db.o: In function `Unserialize':
/home/miner2/src/doublec-i0coin-6fef194/src/main.h:1242: undefined reference to `int ReadWriteAuxPow(CDataStream&, boost::shared_ptr&, int, int, CSerActionUnserialize)'
obj/db.o: In function `Serialize':
/home/miner2/src/doublec-i0coin-6fef194/src/main.h:1242: undefined reference to `int ReadWriteAuxPow(CDataStream&, boost::shared_ptr const&, int, int, CSerActionSerialize)'
obj/net.o: In function `ThreadMapPort2(void*)':
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:859: undefined reference to `upnpDiscover'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:866: undefined reference to `UPNP_GetValidIGD'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:938: undefined reference to `freeUPNPDevlist'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:897: undefined reference to `UPNP_AddPortMapping'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:940: undefined reference to `FreeUPNPUrls'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:902: undefined reference to `strupnperror'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:872: undefined reference to `UPNP_GetExternalIPAddress'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:924: undefined reference to `UPNP_AddPortMapping'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:929: undefined reference to `strupnperror'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:909: undefined reference to `UPNP_DeletePortMapping'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:911: undefined reference to `freeUPNPDevlist'
/home/miner2/src/doublec-i0coin-6fef194/src/net.cpp:912: undefined reference to `FreeUPNPUrls'
collect2: ld returned 1 exit status
make: *** [i0coind] Error 1
uname -a
Linux miner2 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:24 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux