Magento 2 upgrade 2.1.7 to 2.3.2 give error Foreign key constraint is incorrectly formed modify column customer_group_id in table of customer_group

Can anyone please explain about this type of error solution.

Also, I refer to this link Magento 2 failed database rollback cannot add foreign key constraints but not working for me.

so please anyone help me.

Thank you in advance.

Invalid response line returned from server: HTTP/2 200 – message after update to 2.1.7

I seem to be getting this message after i updated to Magento 2.1.7 – it only displays on the contact page when someone submits the form.

Invalid response line returned from server: HTTP/2 200

I see this in the magento log file:

main.CRITICAL: Notice: Array to string conversion in /home/xxx/public_html/vendor/magento/module-catalog/Block/Product/View/Attributes.php on line 83 [] []

Django 2.1.7, IntegrityError, FOREIGN KEY constraint failed

I have a problem with ForeignKey. Or rather, when creating the ForeignKey for the Custom User Model, an error appears:

#CustomUserModel class Usr(AbstractBaseUser): username = models.CharField(max_length=30, validators=[     RegexValidator(             regex=USERNAME_REGEX,             message='Username must be alphanumeric or numbers',             code='invalid_username'     ) ], unique=True)   objects = UsrManager()    is_active = models.BooleanField(default=True) is_admin = models.BooleanField(default=False) is_staff = models.BooleanField(default=False) is_superuser = models.BooleanField(default=False)   def has_perm(self, perm, obj=None):      # Simplest possible answer: Yes, always     return True  def has_module_perms(self, app_label):      # Simplest possible answer: Yes, always     return True   USERNAME_FIELD = 'username' REQUIRED_FIELDS = []  #Model with ForeignKey  class Posts(models.Model): title = models.CharField(max_length=50, unique=True) text = models.CharField(max_length=300) author = models.OneToOneField(get_user_model() ... default=1,  swappable=True, related_query_name='post', db_constraint=True,  related_name='posts', on_delete=models.CASCADE) 

I apologize in advance for possible flaws in the code and grammatical errors. Thank you in advance!