when using Spyder, "an error occurred while starting the kernel" appears. Spyder reported an error attributeerror: type object 'ioloop' has no attribute 'initialized'

Solution:

Search the online methods as follows:
method 1:
Restart Spyder:
the command is Spyder — reset

“An error occurred while starting the kernel” still appears after trying.

Method 2:
enter CONDA update Spyder ipykernel tornado pyzmq
in the terminal. This is also tried, but still an error is reported

The following three methods are finally solved. It is said that the version of tornado is too high. After checking that my version is 6.0, I uninstalled the original version and reinstalled a lower version.

 pip uninstall tornado
 pip install tornado==4.5.3：