This error typical indicates that pycurl is loading a libcurl linked against an incompatible OpenSSL version. The dynamic linker is likely picking up the wrong libcurl (often from a leftover custom install, such as a MySQL bundle), instead of the system one.

Symptom

Running yum (or any Python that imports pycurl) fails with:

/usr/lib64/python2.7/site-packages/pycurl.so: undefined symbol: CRYPTO_num_locks

Diagnose the mislinked library

1. Inspect which shared libraries pycurl resolves at runtime:

ldd /usr/lib64/python2.7/site-packages/pycurl.so

• Look specifically at the path for libcurl.so. If it points to something under /usr/local, a vendor-specific directory, or a non-standard path, that’s a red flag.

2. See what ldconfig knows about libcurl and where it prefers to load it from:

ldconfig -v | grep -E 'libcurl(\.so)?'

If multiple libcurl entries appear, note their directories. A non-system copy (for example, under /usr/local/lib or a MySQL-installed directory) may be shadowing the system libcurl.

3. List the cached candidates and their origins:

ldconfig -p | grep -E 'libcurl(\.so)?'

This confirms which libcurl paths are registered in the dynamic linker cache.

Correct the linker search paths

1. Review custom linker paths that might prioritize a non-system libcurl. Check the main config and drop-ins:

grep -H . /etc/ld.so.conf /etc/ld.so.conf.d/*.conf

If you see entries adding directories for a custom stack (e.g., a MySQL-provided lib directory), consider removing or commenting them out. For example:

vi /etc/ld.so.conf

• Remove or comment any line that injects a “local lib” ahead of system libs (such as /usr/local/lib or a vendor-specific lib directory) if it contains an incompatible libcurl.

2. If a stray library directory was installed by a package you’ve already removed (e.g., a MySQL bundle that dropped its own libcurl), delete or rename that directory so it can’t be picked up:

# Example: adjust to the actual path you identified
mv /usr/local/mysql/lib /usr/local/mysql/lib.bak

3. Rebuild the dynamic linker cache:

ldconfig

4. Verify the cache and linkage again:

ldconfig -p | grep curl
ldd /usr/lib64/python2.7/site-packages/pycurl.so

• Ensure libcurl now resolves to the system path (typically under /usr/lib64 or /usr/lib on RHEL/CentOS).

Test yum

Once libcurl resolves to the correct system library, retry yum:

yum search pycurl

If the commmand runs without the CRYPTO_num_locks error, the mislinked libcurl has been removed from the search path and the issue is resolved.