# Error throws on clicking the plus button at Many2Many list
**URL:** https://discuss.tryton.org/t/error-throws-on-clicking-the-plus-button-at-many2many-list/8794
**Category:** Developer
**Created:** [August 25, 2025, 5:34pm UTC](https://discuss.tryton.org/t/error-throws-on-clicking-the-plus-button-at-many2many-list/8794 "2025-08-25T17:34:53Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@bromoapp](https://discuss.tryton.org/u/bromoapp)
#### Post date: [August 25, 2025, 5:34pm UTC](https://discuss.tryton.org/t/error-throws-on-clicking-the-plus-button-at-many2many-list/8794/1 "2025-08-25T17:34:53Z")
I have 3 related classes:
The **1st** is:
```auto
class Note(ModelSQL, ModelView):
'Note'
__name__ = 'ltl.common.note'
date = fields.Date('Date', required=True, states={
'readonly': True
})
note = fields.Text('Note')
@classmethod
def default_date(cls):
return datetime.today()
```
The **2nd** is:
```auto
class ProjectNote(ModelSQL, ModelView):
'Project Note'
__name__ = 'ltl.project.note'
project = fields.Many2One('ltl.project', 'Project', required=True)
note = fields.Many2One('ltl.common.note', 'Note', required=True)
```
The **3rd** is:
```auto
class Project(ModelSQL, ModelView):
'Project'
__name__ = 'ltl.project'
name = fields.Char('Name', required=True)
remarks = fields.Many2Many('ltl.project.note', 'project', 'note', 'Remarks',
states={
'readonly': Eval('id', -1) < 0
},
depends=['id'],
domain=[
('project', '=', Eval('id'))
]
)
```
I dunno why, but the **domain** at **remarks** field in the **3rd** class has cause:
```auto
[Mon Aug 25 17:27:29 2025] ERROR:trytond.protocols.dispatcher:ltl.common.note.search([[['project', '=', 1]], ...], 0, 1000, None, {'client': '706d045c-5270-40f...', 'language': 'en', 'language_directio...': 'ltr', 'groups': [1, 4]}) from admin@127.0.0.1/tryton/ in 0 ms [dispatcher.py:253]
Traceback (most recent call last):
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/protocols/dispatcher.py", line 216, in _dispatch
result = rpc.result(meth(*c_args, **c_kwargs))
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/model/modelsql.py", line 1819, in search
super().search(
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/model/modelstorage.py", line 711, in search
check_domain(domain, cls, to_check)
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/model/modelstorage.py", line 695, in check_domain
check_domain(d, cls, to_check)
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/model/modelstorage.py", line 695, in check_domain
check_domain(d, cls, to_check)
File "/home/tryton/project/.env/lib/python3.10/site-packages/trytond/model/modelstorage.py", line 674, in check_domain
field = cls._fields[local]
KeyError: 'project'
```
Why is the **domain** cause error while in **ltl.project.note** it has **project** field?
When I take out the **domain** all are fine, its just listing the un-related notes which I don’t want it.
Bromo
---
### Author:  [@ced](https://discuss.tryton.org/u/ced)
#### Post date: [August 25, 2025, 10:05pm UTC](https://discuss.tryton.org/t/error-throws-on-clicking-the-plus-button-at-many2many-list/8794/2 "2025-08-25T22:05:56Z")
> [@bromoapp](#):
>
> ```auto
> domain=[
> ('project', '=', Eval('id'))
> ]
>
> ```
The domain of a `Many2Many` field is on the target model not the relation model.
So I do not think you need this domain at all.
---
### Author:  [@system](https://discuss.tryton.org/u/system)
#### Post date: [August 26, 2025, 10:06pm UTC](https://discuss.tryton.org/t/error-throws-on-clicking-the-plus-button-at-many2many-list/8794/3 "2025-08-26T22:06:13Z")
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