Message type: E = Error
Message class:  CNV_CMIS_M - Message class for CMIS Migration 
Message number: 026
Message text: Cannot read code model include &
The system produces generated code with the aid of a "model". This is an
ABAP include that is used as the basis of the new program. However,  an
error has occurred because the system cannot read this model. The most
likely cause of the problem is that the model is not in the system.
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 CNV_CMIS_M026 ("Cannot read code model include &") typically occurs in the context of SAP's Code Migration and Conversion tools, particularly when dealing with code models during a system conversion or upgrade process. This error indicates that the system is unable to read a specific code model include file, which is essential for the conversion process.
Causes:
Missing Include File: The specified include file may not exist in the system or may have been deleted or moved.
Authorization Issues: The user executing the conversion may not have the necessary authorizations to access the include file.
Incorrect Configuration: There may be a misconfiguration in the conversion settings or parameters that point to the include file.
Transport Issues: If the include file was transported from another system, there may have been issues during the transport process that resulted in the file not being available.
System Errors: There could be underlying system issues, such as database Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_CMIS_M025 No rules are defined for package &
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_CMIS_M024 Not all active rules for package & have mapping values
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_CMIS_M027 Marker &1 cannot be found in the &2 code model
What causes this issue?  Generated code is produced with the aid of a "model". This is an ABAP include that is  used as the basis of the new...
CNV_CMIS_M028 There are currently no unresolved conflicts
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.