3142237 - SPAM: BUFFER_NOT_EMPTY in CHECK_REQUIREMENTS phase

While using SPAM, the queue defined is stopped at CHECK_REQUIREMENTS phase with error BUFFER_NOT_EMPTY.

On the below example, TCI package SAPK61800ACPECCDIMP (SAP Note 3028788) is being imported in SPAM.

Checking the Action Log ("SPAM" > "Goto" > "Action Log"), you see entries similar to the following:
...
Import phase 'CHECK_REQUIREMENTS' (DD.MM.YYYY, HH:mm:ss)
The tp buffer contains old, not completely processed OCS Packages
Interrupt the import due to an error situation (DD.MM.YYYY, HH:mm:ss)
Display detailed informations concerning the error in phase 'CHECK_REQUIREMENTS'
Abort the import due to an error situation (DD.MM.YYYY, HH:mm:ss)

The buffer (<DIR_TRANS>/buffer/<SID>) has the entry for the package. You see something similar to the below:
...
# buffer modified on YYYYMMDDHHmmss implicitly  (transport request ...)
# buffer modified on YYYYMMDDHHmmss (transport request ...)
# buffer modified on YYYYMMDDHHmmss (transport request ...)
/0/SAPK61800ACPECCDIMP XXXXXXXXXXX           *000XXX   XX   XX   X    0    0    0    0    XX   XX   XX   0    0    0    0    0    X                   X  YYYYMMDDHHmmss00000000

Note: this issue is not restricted to this package above, the information shown here is just an example for better understanding.

SAP systems running on SAP NetWeaver - All releases

Update, Support Packages, TCIs, Implementation, Import, Queue, Software update manager, CHECK_REQUIREMENTS, BUFFER_NOT_EMPTY, SPAM, buffer, OCS packages , KBA , BC-UPG-OCS-SPA , Support package tools for ABAP , Problem