Hi, I have a question which really blocked me a long time, many thanks for any help! 1. When I install a RPM package, it always reports "libstdc++.so.6(GLIBCXX_3.4.21)(64bit) is needed by". # rpm -ivh cnet-c-0.1.0-18.9.x86_64.rpm error: Failed dependencies: libstdc++.so.6(GLIBCXX_3.4.21)(64bit) is needed by cnet-c-0.1.0-18.9.x86_64 2. Based on the search, I use following commands to check the dynamic libstdc++.so installation. The version to GLIBCXX_3.4.22 has been installed and the libstdc++.so.6 points to libstdc++.so.6.0.22. /usr/lib64/libstdc++.so.6 -> libstdc++.so.6.0.22 Any suggestions how I should do to solve the dependency issue? And whether I need to downgrade the GLIBCXX_3.4.22 to GLIBCXX_3.4.21? Thanks very much for any help! [root@netconfc-darcy SPECS]# strings /usr/lib64/libstdc++.so.6 | grep GLIBCXX GLIBCXX_3.4 GLIBCXX_3.4.1 GLIBCXX_3.4.2 GLIBCXX_3.4.3 GLIBCXX_3.4.4 GLIBCXX_3.4.5 GLIBCXX_3.4.6 GLIBCXX_3.4.7 GLIBCXX_3.4.8 GLIBCXX_3.4.9 GLIBCXX_3.4.10 GLIBCXX_3.4.11 GLIBCXX_3.4.12 GLIBCXX_3.4.13 GLIBCXX_3.4.14 GLIBCXX_3.4.15 GLIBCXX_3.4.16 GLIBCXX_3.4.17 GLIBCXX_3.4.18 GLIBCXX_3.4.19 GLIBCXX_3.4.20 GLIBCXX_3.4.21 GLIBCXX_3.4.22 # ll /usr/lib64/libstdc++.so.6 lrwxrwxrwx. 1 root root 19 Sep 6 05:16 /usr/lib64/libstdc++.so.6 -> libstdc++.so.6.0.22 Thanks Darcy