GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference

Question

Apologies, I understand questions very similar to this have been asked relatively often, although none of the solutions seem to work for me.When attempting to run any c++ code o

Answer 1

So I was having the same error on ubuntu 18.04, and these are the steps to fix it:

1. Run this to check the what is missing

strings /usr/lib/x86_64-linux-gnu/libstdc++.so.6 | grep GLIBCXX

You will get something like

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_DEBUG_MESSAGE_LENGTH

Then run:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test

sudo apt-get update

sudo apt-get install gcc-5

sudo apt-get upgrade libstdc++6

At least run again to confirm the changes

strings /usr/lib/x86_64-linux-gnu/libstdc++.so.6 | grep GLIBCXX