This article is pretty short and to the point. If you are user of Anaconda you might have or would be encountered with this error. The possible issue that might cause this error is outdated navigator. Here the solution which solved my issue. It is well tested and Yes! it works.
Open the terminal in your system. And follow the command below.
$ conda update conda $ conda update anaconda-navigator $ conda update navigator-updater $ anaconda-navigator --reset
Don’t forget to restart anaconda navigator or restart your computer. Enjoy!