1864952 - XPRAS phase error: Enhancement Spot / BADI is unknown or has been repaired

During an Upgrade or Enhancement Package implementation, you face a syntax error in XPRAS phase similar to the following:

Runtime Errors         SYNTAX_ERROR
Date and Time          03.03.2009 16:20:59

Short text
   Syntax error in program "SAPLFAGL_VIEWS_GENERATE ".

What happened?
    Error in the ABAP Application Program

    The following syntax error occurred in the program
SAPLFAGL_VIEWS_GENERATE :
    "The type "FAGL_HDB_VIEW_GENERATION" is unknown."

Error analysis
 
    The following syntax error was found in the program
SAPLFAGL_VIEWS_GENERATE :
    "The type "FAGL_HDB_VIEW_GENERATION" is unknown.

Another common example:

Runtime Errors         SYNTAX_ERROR
Date and Time          13.10.2011 06:25:19

Short text
   Syntax error in program "CL_PROXY_SERVICE==============CP".

What happened?
    Error in the ABAP Application Program

    The following syntax error occurred in the program
"CL_PROXY_SERVICE==============CP " in include
"CL_PROXY_SERVICE==============CM00D " in
 line 94:
"The type "SPRX_BADI_GENERATION_ALLOWED" is unknown." 

Sometimes a BADi might have been repaired:

A4 EENHANCEMENT 481 Class pool "CL_IM_HRPIQNLPROCESSDBUPD_SL4" of BAdI implementation "HRPIQNLPROCESSUPDSL4" has been repaired
A4 EENHANCEMENT 481 Class pool "CL_IM_HRPIQNL_ADDR_UPD_SL4" of BAdI implementation "HRPIQNL_ADDR_UPDSL4" has been repaired
A4 EENHANCEMENT 481 Class pool "CL_IM_HRPIQNL_CRIHO_ADDR2" of BAdI implementation "HRPIQNL_CRIHO_ADDR2" has been repaired
A4 EENHANCEMENT 481 Class pool "CL_IM_HRQAPBS_2001_CHECK" of BAdI implementation "HRQAPBS_2001_CHECK" has been repaired
A4 EENHANCEMENT 481 Class pool "CL_IM_HRQAPBS_QUOTA_COMPEN" of BAdI implementation "HRQAPBS_QUOTA_COMPEN" has been repaired
A2EEENHANCEMENT 475 Multiple active implementations for definition "HRALE00INBOUND_IDOC"

The BADI or Enhancement Spot object type can vary, please check the "Keywords" section for a list of common objects involved on this issue.

You're unable to proceed with the upgrade

SAP NetWeaver Release Independent.

MAIN_NEWBAS, XPRAS_SHD_AIMMERGE, xpras_aimmrg, XPRAS_TRANS, update, support, package, spam, saint, tp, R3trans, table, definition, netweaver, NW, ERP, ECC, SUM, BADI_PLM_AUDIT_LIST_ITEM_TYPES, CL_PROXY_SERVICE, CL_PROXY, BADI_POWL_TYPE, POWL, CL_SA_TAB_DOCU, SPRX_PROXY_GENERATION_ALLOWED, SAPLPA_PACKAGE_CHECKS, WB_PACKAGE_COMPONENT_CHECK, XPRASUPG, CALENDAR_DEFINITION, BUPA_INBOUND, SPRX_PROXY_ACTIVATION, SECLOG_ALV_GRID, BADI_ALV_GRID, PLM_AUDIT_LIST_ITEM, SE20, CUST, SAPup, inactive, version, active, SE11, SE14, database, dictionary, ABAP, BADI, CL_SA_TAB_DOCU, SOLAR_DOCUMENT_PRINT, BADI_RECA_BUSINESS_OBJECT, CL_NWBC_RUNTIME, HRBAS_PD_PA_INTEGRATION, business, add-in, CL_PROXY_LISTENER, SAPCND/ENGINE_TYPE, ES_UPARO_IMPLEMENTATION, SFW_SWITCH_DETERMINE_OBJ CLS_CHARACTERIZATION , KBA , BC-DWB-CEX , Customer Extensions , BC-UPG , Upgrade - general , BC-EHP , Enhancement Package , Problem