Hello all, I have been dealing with this problem for a long time and I have finally found the reason for this problem and a solution, so I'm publishing it here to help people that might have the same problem.

This happens when you had defined a new field on a custom module -> installed the module -> later you decided yo no longer need that field so you delete it in your custom module (or someone else deletes the field, you update the project with 'pull') and then you update the module on Odoo.

The solution would be:

​1) Find the module in which the field was defined (this might be hard, as the field is already deleted when you have this error)

​2) Uninstall the module (warning: just updating the module doesn't work, I've already tried it many times)

​3) Install the module again

It might look stupid to unistall and reinstall the module again instead of jus updating it but trust me it works. The dificult part here is to find the module in which the field has once been defined, as it not longer exists in the module and it becomes even harder if it wasn't you who deleted the field on de module (maybe a colleague deleted it, you updated the project from git, and now you are unable to find the field in the project, so you can't find where it was defined).

I solved this by uninstallling and then reinstalling the customed module. Hope it works

The error message “Uncaught Promise > Missing field string information” suggests that either the field you’re trying to use from the hr.employee model is missing or it’s not correctly defined. Additionally, the RPC_ERROR during module upgrade could be related to database issues or server configuration.

my error was about missing string on "unsplash_access_key" field i searched "unsplash" and found module named "web_unsplashed" installing it solved my problem ^^

Heres something similar;
https://www.youtube.com/watch?v=r307bAgDVJc

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Most likely there is a custom module that needs to be installed and or updated. You can just check where the field created. If studio > try to update the studio, or fix from views point of view: comment out those field expecting odoo did not read to load and create a new one.

This problem happens if the model is redefined in another place and instead, of using the _inherit you used _name >>> check in the Technical menu > model > your model name ... in order to see where  is inherited  and fix

I have a similar situation right now. I am simply trying to add a Many2one field referencing hr.employee to my custom module.

Literally just this: employee_id = fields.Many2one('hr.employee', string="Employee")
And in the view: name="employee_id"/>

And I get this as an error: Uncaught Promise > Missing field string information
And when I try to upgrade the module I get an RPC_ERROR Odoo Server Error

I'm literally clueless...