Repository: spyder-ide/spyder

Issue:
Bump/remove outdated `spyder-kernerls` `requirements.py` version validation and Spyder crashing
## Problem Description

Spyder crashes (without error message) when starting after updating to newest version 5.2.0 on Windows with the windows installer, when the python interpretor is set to a version which uses an outdated spyder kernel. 

### What steps reproduce the problem?

set Python interpreter in preferences to python version with outdated spyder kernel. Usually an error message appears in the console in such a situatino. But after the update to 5.2.0, Spyder just crashes without any error message. After Performing a Spyder --reset it started again. After Setting again to another python version, it crashed again.

### What is the expected output? What do you see instead?
Spyder wont start, but crashes. Even when using a wrong spyder-kernel version, the program should start up and display an error message, but it does not, just crashes

## Versions
Spyder 5.2.0
Python Version 3.9
Spyder Kernel Version 2.1.0
Windows 10




Discussion:
I think in requirements.py
```
def check_spyder_kernels():
    """Check spyder-kernel requirement."""
    try:
        import spyder_kernels
        required_ver = '2.0.0'
```
is outdated.
Hi @RolBurgHxgn thank you for the feedback! I think your issue regarding Spyder crashing due the spyder-kernels version is a duplicate of #16896 and a fix will be release with Spyder 5.2.1

> I think in requirements.py
> 
> def check_spyder_kernels():
>     """Check spyder-kernel requirement."""
>     try:
>         import spyder_kernels
>         required_ver = '2.0.0'
> 
> is outdated.

However regarding `requirements.py`  I think you are right, we should bump up the version check on that warning :+1:

Resolving patch:
diff --git a/spyder/app/mainwindow.py b/spyder/app/mainwindow.py
--- a/spyder/app/mainwindow.py
+++ b/spyder/app/mainwindow.py
@@ -39,7 +39,6 @@
 from spyder import requirements
 requirements.check_path()
 requirements.check_qt()
-requirements.check_spyder_kernels()
 
 #==============================================================================
 # Third-party imports
diff --git a/spyder/requirements.py b/spyder/requirements.py
--- a/spyder/requirements.py
+++ b/spyder/requirements.py
@@ -55,19 +55,3 @@ def check_qt():
                      "%s %s+\n\n"
                      "are required to run Spyder."
                      % (qt_infos['pyqt5']))
-
-
-def check_spyder_kernels():
-    """Check spyder-kernel requirement."""
-    try:
-        import spyder_kernels
-        required_ver = '2.0.0'
-        actual_ver = spyder_kernels.__version__
-        if parse_version(actual_ver) < parse_version(required_ver):
-            show_warning("Please check Spyder installation requirements:\n"
-                         "spyder-kernels >= 2.0 is required (found %s)."
-                         % actual_ver)
-    except ImportError:
-        show_warning("Failed to import spyder-kernels.\n"
-                     "Please check Spyder installation requirements:\n\n"
-                     "spyder-kernels >= 2.0 is required")


Test patch: