conda update causes ImportError: No module named tqdm

Whenever I try to update anything using conda, I get an error: ImportError: No module named tqdm. Here’s the full traceback:

$ conda update conda
Traceback (most recent call last):
  File "/Users/user/anaconda2/bin/conda", line 13, in <module>
    sys.exit(main())
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/cli/main.py", line 150, in main
    return conda_exception_handler(_main, *args, **kwargs)
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/exceptions.py", line 1335, in conda_exception_handler
    return_value = exception_handler(func, *args, **kwargs)
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/exceptions.py", line 1046, in __call__
    return self.handle_exception(exc_val, exc_tb)
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/exceptions.py", line 1090, in handle_exception
    return self.handle_unexpected_exception(exc_val, exc_tb)
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/exceptions.py", line 1101, in handle_unexpected_exception
    self.print_unexpected_error_report(error_report)
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/exceptions.py", line 1171, in print_unexpected_error_report
    from .cli.main_info import get_env_vars_str, get_main_info_str
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/cli/main_info.py", line 19, in <module>
    from ..core.index import _supplement_index_with_system
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/core/index.py", line 9, in <module>
    from .package_cache_data import PackageCacheData
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda/core/package_cache_data.py", line 15, in <module>
    from conda_package_handling.api import InvalidArchiveError
  File "/Users/user/anaconda2/lib/python2.7/site-packages/conda_package_handling/api.py", line 5, in <module>
    import tqdm
ImportError: No module named tqdm

However, when I try to install tqdm with pip, it says it is already installed:

$ pip install tqdm
Requirement already satisfied: tqdm in /usr/local/lib/python2.7/site-packages (4.32.2)

I am using Python 2.7 on MacOS Mojave with no virtual environments. How can I fix conda?

EDIT:
I also tried: python -m pip install tqdm but it says requirement already satisfied.

Then I tried: /Users/user/anaconda2/bin/python -m pip install tqdm but it also says requirement already satisfied: Requirement already satisfied: tqdm in ./anaconda2/lib/python2.7/site-packages (4.31.1)