Mode of the activity cannot be used by scheduling

What causes this issue?

A mode contains a secondary resource for which at least one of the
following conditions has been violated:
If the secondary resource is a <zh>single resource</>, it <ZH>cannot</>
be assigned a <zh>setup matrix</>.
<zh>No blocks</> may be defined for the secondary resource
If the secondary resource is a <zh>multiresource</>, the
<zh>synchronization of activities</> may <zh>not</> be used for this
resource.
If the secondary resource is a <zh>mixed resource</>, the <zh>bucket
share</> of the capacity may <zh>not</> be scheduled <zh>infinitely</>.
If the secondary resource is a <zh>bucket resource</>, the <ls>Schedule
on Grid</> indicator may not be set.

System Response

The order cannot be created or changed.

How to fix this error?

In the master data for the secondary resource (on the <ls>Planning
Parameters</> and <ls>Block Planning</> tab pages), ensure that none of
the conditions mentioned above are violated.
INCLUDE OM_PP_NICHT_LOES_SYSVER OBJECT DOKU ID TX

Procedure for System Administrators

INCLUDE OM_PP_VORG_FUER_SYSVER OBJECT DOKU ID TX
Return code 287 (om_unusable_mode)
Error code COM API

Error message extract from SAP system. Copyright SAP SE.