Lot or serial number not available to pick, Zentriq

The lot written on the warehouse line has no free quantity left: it is reserved for another document, already committed to a second open activity, or no longer on hand in the quantity requested. Business Central checks availability again when you register, not only when the pick or put-away was created, which is why the line looked fine earlier. Find what holds the quantity, release it or point the line at a lot that is genuinely available, then register again.

Why Business Central blocks the registration

Tracking numbers are not interchangeable. When a pick, put-away or movement line names Lot No. LOT0001, the system has to find that exact lot free in the bin it wants to take it from, and it verifies this at the moment of registration rather than at creation. Between those two moments another user can reserve the lot for a sales order, a second activity can be created for the same quantity, or the goods can be consumed, adjusted out or moved to another bin. Any of those leaves the line pointing at quantity that is no longer available to it.

The lot is physically on hand but reserved for another sales order, production order or transfer, so the quantity is not free for this document.
A second pick, put-away or movement already carries the same lot for the same quantity and has neither been registered nor deleted.
The item tracking on the source document was changed, or the goods were consumed, adjusted or moved to another bin, after the warehouse activity was created.

How to release or correct the line

Note the item and the lot from the message, open the item card and choose Related, then Entries, then Reservation Entries to see which documents hold that lot.
If the quantity is held by a document that is not urgent, open that document line, use its Reserve action and cancel the reservation there, then register again.
If nothing holds it, check the real stock: open Item Ledger Entries and the warehouse entries for the item and confirm the lot still has remaining quantity in the bin the line refers to.
When the lot is genuinely gone, delete the warehouse activity line, correct the item tracking on the source document so it names a lot that is on hand, and create the activity again.
For a partial situation, reduce the quantity to handle on the warehouse line to what is actually free, register that part, and deal with the rest separately.
If the reservations belong to other users or come from an automatic reservation policy on the item, the owner of that order or an administrator has to release them; you cannot always cancel someone else's reservation yourself.

How to avoid it next time

Most cases come from a gap between planning and execution: the same stock is committed twice because two documents were prepared at different moments. Registering warehouse activities promptly, setting the reservation policy on the item card to what the warehouse actually follows, and using Select Entries in Item Tracking Lines so only lots on hand can be chosen all reduce the number of lines that go stale. A short daily review of open picks and put-aways also catches activities that were created and then never registered.

Frequently asked questions

Is the serial number version of this message a different problem?

No, it is the same check. It reads Serial No. SN00123 is not available on inventory or it has already been reserved for another document, and both the causes and the fix are identical.

Can I simply delete the warehouse pick?

Yes. Deleting it releases the lines and returns the quantity to the source document, so you can create the activity again against current availability. Nothing is posted until an activity is registered.

"Lot No. LOT0001 is not available on inventory or it has already been reserved for another document."