Error assert issubclass(cls, PoolBase), cls

Hi i need to activate a module .

My issue is that during the activation of the module it shows me this error:

Traceback (most recent call last):
  File "trytond/bin/trytond-admin", line 21, in <module>
  File "/home/developer/venv/project/trytond/trytond/", line 53, in run
  File "/home/developer/venv/project/trytond/trytond/", line 160, in init
    lang=lang, activatedeps=activatedeps)
  File "/home/developer/venv/project/trytond/trytond/modules/", line 420, in load_modules
  File "/home/developer/venv/project/trytond/trytond/modules/", line 390, in _load_modules
    load_module_graph(graph, pool, update, lang)
  File "/home/developer/venv/project/trytond/trytond/modules/", line 201, in load_module_graph
    classes = pool.fill(module, modules)
  File "/home/developer/venv/project/trytond/trytond/", line 221, in fill
    assert issubclass(cls, PoolBase), cls
AssertionError: <class 'trytond.modules.payroll.payslip.Intervention'>

what does this error mean exactly !!!

It means that you have a class named trytond.modules.payroll.payslip.Intervention that does not inherit from any Model class so it can not be registered in the pool.

You need to make it inherit from some Model or remove it from the pool to fix it.

Or use the metaclass PoolMeta if it is to extend an existing model.

Hi M.@ced, in the module, the class is already defined like that:

class Intervention(metaclass=PoolMeta):

So as @pokoli said it is no a class that extends an existing model so it must at least inherit from Model if it is a model, from Wizard if it is a wizard and from Report if it is a report.