Hello Alex,
when upgrading from EhP 3 or lower to EhP 4 or higher several adjustments to the correspondences and the correspondence customizing have to be applied as the solution for changing letters has be changed completely. Could you check the following:
- confirm that table T77RCF_DOC_CAT contains and entry with key 0004 and an entry with key 0005
- confirm that in table T77RCF_ACT_CAT the value for the document category of the activity category 02 (simple correspondence) is set to 0004
- confirm that in table T77RCF_ACT_CAT the value for the document category of the activity category 04 (invitation) is set to 0005
- check that the interface of a simple correspondence SMARTFORM is exactly the same as HRRCF_CS_IT_APPLICANT (check for the importing parameter THEAD as this a new parameter which was not existing in the EhP 3 referecnce SMARTFORM HRRCF_CS_APPLICANT)
- check that the interface of an invitation SMARTFORM is exactly the same as HRRCF_CS_IT_APPL_INVITATION (check for the importing parameter THEAD as this a new parameter which was not existing in the EhP 3 referecnce SMARTFORM HRRCF_CS_APPL_INVITATION)
- just to be sure check that the mapping of correspondence form to include text module is correct in table T77RCF_INCL2FORM
If all this is correct and the issue persists check if the SMARTFORM for the correspondence is testable in the backend. Simply test it in the backend till you display the print preview. You do not need to fill all parameters. Sometimes the system has issues to generate the function module for a SMARTFORM if the initial call is done via web. The backend test ensures that all runtime elements are generated. Then check if the error persists.
If this is still not solving the issue I recomment to customize one of the example SMARTFORMs with name HRRCF_CS_IT_EXA_* for one of your activities (pay attention to use one which matches the activity category of you activity type. If the interface includes an parameter EVENT the form can be used with activity category 04 (invitation) otherwise with activity category 02 (simple correspondence)). Do not forget to maintain the matching letter section text module in table T77RCF_INCL2FORM. You will find the name of the correct text module if you open the SMARTFORM and look for the text with id "MAIN" in the window "Hauptfenster".
If your scenario is working with the example SMARTFORM there is highly likely a problem with your SMARTFORM implementation. If it is not working you have probably a setup issue. If we can narrow the issue we might be able to have additional ideas.
Next to all of the things above. Please check if you get any information in the application log (SLG1) or if there is a dump (ST22).
Kind regards
Roman