Yum check update error "pycurl.so: undefined symbol: CRYPTO_set_locking_callback"

Solution Unverified - Updated -


  • Red Hat Enterprise Linux 6.4


  • When I run yum, following error occurs:
[root@host tmp]# yum check update
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   /usr/lib64/python2.6/site-packages/pycurl.so: undefined symbol: CRYPTO_set_locking_callback

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.6.6 (r266:84292, Sep  4 2013, 07:46:00)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]

If you cannot solve this problem yourself, please go to
the yum faq at:


  • Check and fix the curl library path or remove 3rd party curl library.

Root Cause

  • 3rd party curl library has been installed.
# ldconfig -p -N -X | grep curl
    libcurl.so.4 (libc6,x86-64) => /usr/lib/libcurl.so.4
    libcurl.so.4 (libc6,x86-64) => /usr/lib64/libcurl.so.4
    libcurl.so (libc6,x86-64) => /usr/lib/libcurl.so

Diagnostic Steps

  • Do an strace on the yum command, you'll probably see it pointing to the problem package or file, like:
open("/usr/lib/libcurl.so.4", O_RDONLY) = 9
  • Output of ldd command in normal system.
# ldd /usr/lib64/python2.6/site-packages/pycurl.so
    linux-vdso.so.1 =>  (0x00007fff9cb7f000)
    libcurl.so.4 => /usr/lib64/libcurl.so.4 (0x00007fc35da43000)  <<--- proper path
    libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00007fc35d69d000)
    libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fc35d47f000)
    libc.so.6 => /lib64/libc.so.6 (0x00007fc35d0eb000)
    libidn.so.11 => /lib64/libidn.so.11 (0x00007fc35ceb9000)
    libldap-2.4.so.2 => /lib64/libldap-2.4.so.2 (0x00007fc35cc68000)
    librt.so.1 => /lib64/librt.so.1 (0x00007fc35ca60000)
    libgssapi_krb5.so.2 => /lib64/libgssapi_krb5.so.2 (0x00007fc35c81c000)
    libkrb5.so.3 => /lib64/libkrb5.so.3 (0x00007fc35c535000)
    libk5crypto.so.3 => /lib64/libk5crypto.so.3 (0x00007fc35c309000)
    libcom_err.so.2 => /lib64/libcom_err.so.2 (0x00007fc35c105000)
    libz.so.1 => /lib64/libz.so.1 (0x00007fc35beee000)
    libssl3.so => /usr/lib64/libssl3.so (0x00007fc35bcaf000)
    libsmime3.so => /usr/lib64/libsmime3.so (0x00007fc35ba83000)
    libnss3.so => /usr/lib64/libnss3.so (0x00007fc35b743000)
    libnssutil3.so => /usr/lib64/libnssutil3.so (0x00007fc35b517000)
    libplds4.so => /lib64/libplds4.so (0x00007fc35b313000)
    libplc4.so => /lib64/libplc4.so (0x00007fc35b10d000)
    libnspr4.so => /lib64/libnspr4.so (0x00007fc35aecf000)
    libdl.so.2 => /lib64/libdl.so.2 (0x00007fc35accb000)
    libssh2.so.1 => /usr/lib64/libssh2.so.1 (0x00007fc35aaa2000)
    libutil.so.1 => /lib64/libutil.so.1 (0x00007fc35a89f000)
    libm.so.6 => /lib64/libm.so.6 (0x00007fc35a61b000)
    /lib64/ld-linux-x86-64.so.2 (0x0000003369800000)
    liblber-2.4.so.2 => /lib64/liblber-2.4.so.2 (0x00007fc35a40b000)
    libresolv.so.2 => /lib64/libresolv.so.2 (0x00007fc35a1f1000)
    libsasl2.so.2 => /usr/lib64/libsasl2.so.2 (0x00007fc359fd7000)
    libkrb5support.so.0 => /lib64/libkrb5support.so.0 (0x00007fc359dcb000)
    libkeyutils.so.1 => /lib64/libkeyutils.so.1 (0x00007fc359bc8000)
    libssl.so.10 => /usr/lib64/libssl.so.10 (0x00007fc35995b000)
    libcrypto.so.10 => /usr/lib64/libcrypto.so.10 (0x00007fc359578000)
    libcrypt.so.1 => /lib64/libcrypt.so.1 (0x00007fc359341000)
    libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fc359121000)
    libfreebl3.so => /lib64/libfreebl3.so (0x00007fc358ea8000)
  • Output of ldd command in problematic system.
# ldd /usr/lib64/python2.6/site-packages/pycurl.so
    linux-vdso.so.1 =>  (0x00007fff973ff000)
    libcurl.so.4 => /usr/lib/libcurl.so.4 (0x00007fe0691d1000) <<<----- might be changed.
    libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00007f110b8af000)
    libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fc35d47f000)
    libc.so.6 => /lib64/libc.so.6 (0x00007fc35d0eb000)
    librt.so.1 => /lib64/librt.so.1 (0x00007fc35ca60000)
    libdl.so.2 => /lib64/libdl.so.2 (0x00007fc35accb000)
    libutil.so.1 => /lib64/libutil.so.1 (0x00007fc35a89f000)
    libm.so.6 => /lib64/libm.so.6 (0x00007fc35a61b000)
    /lib64/ld-linux-x86-64.so.2 (0x0000003369800000)

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