i had a similar problem, Odoo send me this fix:

ARM created a fix for this. In order to implement it you need to follow these steps: 

1.debug mode

2.technical/server actions

3.create

4.action name: e.g. fix unreserved qty

5.model: ir.actions.server

6.action to do: "execute python code"

7.copy/paste the fix underneath the pre-existing code

8."save" 

9."create contextual action"

10.refresh page

11.action/fix "fix unreserved qty"

12.wait for it to load 

13."remove contextual action"

14.action/delete

______

It happens because the reserved quantity in your inventory does not reflect the one on your pickings. It's probably due to a small configuration change while some pickings where open. 

An easy way to remove it is to create a server action that executes this code https://gist.github.com/amoyaux/20d50f3368ef2f552071f718dc65cad4

It should repair all the inconsistencies in your data.

Here is the code for the server action

# Available variables:

#  - env: Odoo Environment on which the action is triggered

#  - model: Odoo Model of the record on which the action is triggered; is a void recordset

#  - record: record on which the action is triggered; may be void

#  - records: recordset of all records on which the action is triggered in multi-mode; may be void

#  - time, datetime, dateutil, timezone: useful Python libraries

#  - log: log(message, level='info'): logging function to record debug information in ir.logging table

#  - Warning: Warning Exception to use with raise

# To return an action, assign: action = {...}

# Available variables:

#  - env: Odoo Environment on which the action is triggered

#  - model: Odoo Model of the record on which the action is triggered; is a void recordset

#  - record: record on which the action is triggered; may be void

#  - records: recordset of all records on which the action is triggered in multi-mode; may be void

#  - time, datetime, dateutil, timezone: useful Python libraries

#  - log: log(message, level='info'): logging function to record debug information in ir.logging table

#  - Warning: Warning Exception to use with raise

# To return an action, assign: action = {...}

quants = env["stock.quant"].search([])

move_line_ids = []

warning = ""

for quant in quants:

    move_lines = env["stock.move.line"].search(

        [

            ("product_id", "=", quant.product_id.id),

            ("location_id", "=", quant.location_id.id),

            ("lot_id", "=", quant.lot_id.id),

            ("package_id", "=", quant.package_id.id),

            ("owner_id", "=", quant.owner_id.id),

            ("product_qty", "!=", 0),

        ]

    )

    move_line_ids += move_lines.ids

    reserved_on_move_lines = sum(move_lines.mapped("product_qty"))

    move_line_str = str.join(

        ", ", [str(move_line_id) for move_line_id in move_lines.ids]

    )

    if quant.location_id.should_bypass_reservation():

        # If a quant is in a location that should bypass the reservation, its `reserved_quantity` field

        # should be 0.

        if quant.reserved_quantity != 0:

            quant.write({"reserved_quantity": 0})

    else:

        # If a quant is in a reservable location, its `reserved_quantity` should be exactly the sum

        # of the `product_qty` of all the partially_available / assigned move lines with the same

        # characteristics.

        if quant.reserved_quantity == 0:

            if move_lines:

                move_lines.with_context(bypass_reservation_update=True).write(

                    {"product_uom_qty": 0}

                )

        elif quant.reserved_quantity < 0:

            quant.write({"reserved_quantity": 0})

            if move_lines:

                move_lines.with_context(bypass_reservation_update=True).write(

                    {"product_uom_qty": 0}

                )

        else:

            if reserved_on_move_lines != quant.reserved_quantity:

                move_lines.with_context(bypass_reservation_update=True).write(

                    {"product_uom_qty": 0}

                )

                quant.write({"reserved_quantity": 0})

            else:

                if any(move_line.product_qty < 0 for move_line in move_lines):

                    move_lines.with_context(bypass_reservation_update=True).write(

                        {"product_uom_qty": 0}

                    )

                    quant.write({"reserved_quantity": 0})

move_lines = env["stock.move.line"].search(

    [

        ("product_id.type", "=", "product"),

        ("product_qty", "!=", 0),

        ("id", "not in", move_line_ids),

    ]

)

move_lines_to_unreserve = []

for move_line in move_lines:

    if not move_line.location_id.should_bypass_reservation():

        move_lines_to_unreserve.append(move_line.id)

if len(move_lines_to_unreserve) > 1:

    env.cr.execute(

        """ 

            UPDATE stock_move_line SET product_uom_qty = 0, product_qty = 0 WHERE id in %s ;

        """

        % (tuple(move_lines_to_unreserve),)

    )

elif len(move_lines_to_unreserve) == 1:

    env.cr.execute(

        """ 

        UPDATE stock_move_line SET product_uom_qty = 0, product_qty = 0 WHERE id = %s ;

        """

        % (move_lines_to_unreserve[0])

    )

This pull request fixes the issue

https://github.com/odoo/odoo/pull/81127/files#diff-4424c1629e21b466bb7af6ab0cb3a674d1bf3e75d93e7e76cf77870dc5bcc853

I was delighted to find a solution for the reservation issue. Some of our MO's are stuck. Unable to cancel or finish since one or more of the components cannot be "unreserved". We recently upgraded from version 7 to version 12.

Unfortunately running the proposed server action on V12 enterprise (odoo.sh) did not resolve our problem.

Odoo Enterprise support did identify the cause of the problem in our case. 

The Decimal Accuracy/Product Unit of Measure the number of digits was set to 3, while the rounding precision of Unit of Measure (UOM) "kg" was 0.000001

[In general:

If Decimal Accuracy is 3 digits, UOMs should have rounding precision 0.01000 , 0.00100 but not 0.00010 or 0.00001 

If Decimal Accuracy is 2 digits, your UOMs should have rounding precision 0.01000 but not 0.00100, 0.00010 or 0.00001] 

Adjusting the rounding precision took care of some stuck MO's but not all of them. Support did correct historic transactions and all looks fine now.

So kudos to Odoo support for this one. Hope it may help someone else down the road.

Hi,

This code indeed solves the inconsistency in my database and let's my client continue workign. 

However, it keeps happenning again and again. There are not any "configuration changes" in between the failures. 

Do you have any hints on why could this be happenning?

Thanks

V15 FIX: I researched a fix using the code below, and Odoo internal informed me that since v11 (currently we're v15) this code fix sometimes works. Clicking 'update this app' from the Apps list also sometimes works. Your best bet is to submit a ticket to get this issue resolved. 

Sorry,

I got until p.to  6.action to do: "execute python code"
and I got this in Phyton code

# Available variables:

#  - env: Odoo Environment on which the action is triggered

#  - model: Odoo Model of the record on which the action is triggered; is a void recordset

#  - record: record on which the action is triggered; may be void

#  - records: recordset of all records on which the action is triggered in multi-mode; may be void

#  - time, datetime, dateutil, timezone: useful Python libraries

#  - log: log(message, level='info'): logging function to record debug information in ir.logging table

#  - Warning: Warning Exception to use with raise

# To return an action, assign: action = {...}

https://gist.github.com/amoyaux/20d50f3368ef2f552071f718dc65cad4
page not found,

https://gist.github.com/amoyaux/20d50f3368ef2f552071f718dc65cad4
this too, page not found

the python code linked in this answer disappeared from the Github account. What to do now?

The way i did is in the fallowing video  and it worked .. 

you will endup having a component not consumed, but you can at least mark as done the MO
https://screencast-o-matic.com/watch/c3jZlDVTONK

I'm on V 14 community and the code provided is good as long as it works. At the beginning it took 5 minutes to run it, now it takes 40-60 minutes and quite often throws an error making it almost impossible to use. In our case we get this "unreserved" error when trying to validate the sale order delivery. The work around I found is to go to database and increase stock_quant.reserved_quantity to the quantity slightly higher than quantity reserved in that specific sale order delivery for a specified lot number of a product that produces the error (we use lots). Not sure if this lot is also reserved for other sale orders and that should be also taken into account.

Just wondering if that issue was ever resolved in the latest V14 versions?

On version 14 and receiving the same issue. I can make this happen almost at will by continuing to issue product to a manufacturing order once it is "In-Process". Sometimes the above works, other times it does not. This is a BIG issue in that it is important for manufacturing to be able to issue additional product to the MO after the MO has began to be processed.

Hello

I did not get the steps

10.refresh page    (means simply reloading ??)

11.action/fix "fix unreserved qty"   (my action button on top has only delete or duplicate?)

thanks for help

Jan

ps. fixed my error! and fixed the Odoo error !!!   Great thanks a lot!!!

Please anyone give me solution i am facing problem when i validate delivery order it shows error

It is not possible to unreserve more products of [VG1560080012] SPIN-ON FUEL FINE FILTER than you have in stock.
Does not validate stock in odoo 11 community

Hi,

Enable debug mode and navigate to server action menu under settings and see if there is a server action named:  Correct inconsistencies for reservation

If found, click on Run button, which will solve the issue, if server action is not found, pull the latest source code of corresponding odoo version and upgrade the stock module.

More info:  https://github.com/odoo/odoo/commit/e0e63be484b0ebddc7d498a4a13b2ba7a7f1a1f4#diff-c0d27a4adc8bbd305125f4e2729e30fe444fdd4e5ca0f96f2dd7f1fab19fe80eR17

Thanks

Hi, Julia

i did all your steps, but i did n't understand in step 9

9."create contextual action"
please where i can create this step?