A line on the shipment reads Blocked, or committing does nothing. Here is what to check.
There is nothing available to pick
Blocked means exactly that — no stock is free to reserve for this line right now.
That is not the same as having none. The stock can be sitting in your warehouse and still be unavailable, because it is already committed to someone else's order.
Check: open the item and look at Available to pick, not On Hand. If it is 0, the stock is spoken for.
Another order got there first
Committing is first come, first served. An order confirmed after yours can commit before yours if someone acted on it sooner.
Check: look at what else is committed for that item. If an order that matters less is holding the stock, uncommit it and the stock returns to available to pick — see Undo a shipping step.
The order is not confirmed
You cannot ship a Saved order. Open it and click Save & confirm Sales Order.
The stock is in a different warehouse
An order can only be filled from the warehouse it was raised against. Stock sitting in another one does not count.
Check: the warehouse on the order against where the stock actually is.
Available is showing a negative number
That is normal and it is not the cause. Confirming an order for more than you hold is allowed — it is how backorders work. The order sits and waits for stock.
Still stuck?
Send us these and we can trace it:
the sales order number
the item's SKU code
what On Hand and Available to pick are showing
any other order numbers you think are holding the stock