Conda / Anaconda will not update ANY PACKAGE due to environment inconsistency

Question

I am trying to update/install several packages in conda (I've also tried in Anaconda navigator, it goes nowhere and provides no helpful status information). I keep getting the error:

The environment is inconsistent, please check the package plan carefully
The following packages are causing the inconsistency:

  - defaults/linux-64::blaze==0.11.3=py37_0
  - defaults/linux-64::numba==0.41.0=py37h962f231_0
  - defaults/linux-64::pytables==3.4.4=py37ha205bf6_0
  - defaults/linux-64::anaconda==2018.12=py37_0

I have read a lot of very similar issues here and on other forums, and tried the following:

$ conda update <package> for the packages listed, individually and as a group

$ conda install <package> for same

$ conda update --all

$ conda update python

$ conda install python

$ conda update conda

$ conda install conda

That covers all the suggestions that I have seen in forums, and understood. In every case, I get the error above, followed, after a minute or two by:

failed with initial frozen solve. Retrying with flexible solve.
Solving environment: / 
Found conflicts! Looking for incompatible packages.
This can take several minutes.  Press CTRL-C to abort.

This is followed by a several hours long attempt to resolve the environment, which then fails.

OS: Ubuntu 18.04

conda: 4.8.4

python: 3.7.8

Does anyone have any ideas beyond what I've tried?

Answer 1

I was the same issue after a recent update to my environment.

I used conda list --revision to check the last version before this happened and then conda install --revision <rev num> to rollback to the latest working version of my environment and that worked for me.