undefined reference to '__dlsym'

This error message usually indicates that the linker is unable to find a reference to the '__dlsym' function. This function is used to obtain the address of a symbol in a shared library, and is part of the dynamic linker library.

The most common cause of this error is a missing or incorrectly-linked library. If you are building your own program, you may need to add the library that contains the '__dlsym' function to your linker flags. If you are using a pre-built library, you may need to ensure that it is installed correctly and that your linker is able to find it.

Another possible cause of this error is a version mismatch between the library and the dynamic linker. If the library was built against a different version of the dynamic linker than the one you are using, it may not be able to find the '__dlsym' function. In this case, you may need to update either the library or the dynamic linker to ensure compatibility.

Overall, this error can be difficult to diagnose without more information about the specific context in which it occurs. If you are encountering this error, you may need to consult documentation or seek help from a more experienced developer to find a solution.