Message type: E = Error
Message class:  VHUMI - Messages for material identification 
Message number: 155
Message text: HU & contains items of HU-managed and non HU-managed storage locations
HU &V1& contains items (materials or HUs), that refer both to
HU-managed storage locations as well as storage locations that are not
HU-managed.
HU &V1& cannot be created.
Only pack materials or HUs in an HU that refers only to
HU-managed storage locations
Storage locations that are not HU-managed
In Customizing, check whether a storage location is HU-managed under
<ls><DS:SIMG.SIMG_MMIM_MB_DELIV>HU-requirement</>for storage locations
and default values</>.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message VHUMI155 indicates that there is a conflict between handling units (HUs) that contain items from both HU-managed and non-HU-managed storage locations. This situation arises when you attempt to perform operations (like goods movements, transfers, or inventory management) involving handling units that are not compatible due to the differing management methods.
Cause: Mixed Storage Locations: The handling unit contains items that are stored in both HU-managed and non-HU-managed storage locations. This can happen if the items in the handling unit are from different storage types or if the configuration of the storage locations allows for both types of management.
Configuration Issues: The storage location settings in the SAP system may not be properly configured to handle mixed storage types. Inconsistent Data: There may be inconsistencies in the master data for the materials involved, such as incorrect settings for HU management.
Solution: Separate Handling Units: Ensure that handling units only contain items from either
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
VHUMI154 HU & does not contain any material items
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
VHUMI153 HU & can only be packed in HUs of a non HU-managed storage location
What causes this issue?  You tried to pack HU &V1& in HU &V2&.System Response  This cannot be done because HU &V2&  is stored ...
VHUMI156 Plant and storage location of all HU items must be the same
What causes this issue?  HU &V1& is to be created with an HU-managed storage location and contains materials or HUs that are assigned to diffe...
VHUMI157 Reservation item &1: plant &2 invalid
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.