diff --git a/CMakeLists.txt b/CMakeLists.txt
index d5ef55de09..5225ff76ea 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -352,13 +352,19 @@ string(TIMESTAMP UTC_NOW "%Y-%m-%dT%H-%MZ" UTC)
 # Set AIO directory path used by multiple targets below
 set(AIO_DIR "${CMAKE_CURRENT_BINARY_DIR}/aio")
 
-# Robocopy wrapper for Windows incremental file copy (used by deployment targets)
+# Robocopy wrapper for Windows incremental file copy (used by deployment targets).
+# We invoke through `cmd /c "<absolute-path>"` rather than the bare wrapper path because
+# modern Windows refuses to execute scripts from the current directory without an explicit
+# `.\` prefix, and CMake strips the absolute path on COMMAND args that live inside
+# CMAKE_BINARY_DIR (the custom-build CWD). Treating the wrapper as an argument to cmd
+# keeps the absolute path intact in the generated MSBuild command.
 if(WIN32)
-    set(ROBOCOPY_WRAPPER "${CMAKE_BINARY_DIR}/robocopy_wrapper.cmd")
+    set(ROBOCOPY_WRAPPER_PATH "${CMAKE_BINARY_DIR}/robocopy_wrapper.cmd")
     file(
-        WRITE ${ROBOCOPY_WRAPPER}
+        WRITE ${ROBOCOPY_WRAPPER_PATH}
         "@echo off\r\nrem Robocopy wrapper: forwards all args to robocopy and normalizes exit codes\r\nrobocopy %*\r\nset rc=%ERRORLEVEL%\r\nif %rc% GEQ 8 exit /b %rc%\r\nexit /b 0\r\n"
     )
+    set(ROBOCOPY_WRAPPER cmd /c "${ROBOCOPY_WRAPPER_PATH}")
 endif()
 
 # #######################################################################################################################
@@ -418,14 +424,20 @@ if(AUTO_PLUGIN_DEPLOYMENT OR AIO_ZIP_TO_DIST)
 
     # Prepare AIO only when sources change. Gather package + feature files as
     # inputs so the prepare step runs only when something actually changed.
+    # Shader files are intentionally excluded - copy_shaders.stamp owns those,
+    # and including them here causes a race where two parallel custom-build
+    # rules call cmake -E copy_if_different on the same destination file
+    # (Permission denied on Windows when one process has it open for write).
     file(
         GLOB_RECURSE _AIO_PACKAGE_FILES
         LIST_DIRECTORIES FALSE
         "${CMAKE_SOURCE_DIR}/package/*"
     )
     list(FILTER _AIO_PACKAGE_FILES EXCLUDE REGEX "/Tests/")
+    list(FILTER _AIO_PACKAGE_FILES EXCLUDE REGEX "/Shaders/")
     foreach(_fpath IN LISTS FEATURE_PATHS)
         file(GLOB_RECURSE _tmp LIST_DIRECTORIES FALSE "${_fpath}/*")
+        list(FILTER _tmp EXCLUDE REGEX "/Shaders/")
         list(APPEND _AIO_PACKAGE_FILES ${_tmp})
     endforeach()
 
@@ -457,16 +469,21 @@ if(AUTO_PLUGIN_DEPLOYMENT OR AIO_ZIP_TO_DIST)
         "${CMAKE_SOURCE_DIR}/cmake/CleanupStaleEntries.cmake"
     )
 
-    # Copy package files (exclude test files from production packages)
+    # Copy package files (exclude test files from production packages, and
+    # exclude shaders since copy_shaders.stamp owns those - see input-tracking
+    # comment above for the race-condition rationale).
     file(
         GLOB_RECURSE _AIO_PACKAGE_SOURCE_FILES
         LIST_DIRECTORIES FALSE
         "${CMAKE_SOURCE_DIR}/package/*"
     )
     list(FILTER _AIO_PACKAGE_SOURCE_FILES EXCLUDE REGEX "/Tests/")
+    list(FILTER _AIO_PACKAGE_SOURCE_FILES EXCLUDE REGEX "/Shaders/")
     append_copy_if_different(_prepare_aio_cmds _AIO_PACKAGE_SOURCE_FILES "${CMAKE_SOURCE_DIR}/package" "${AIO_DIR}")
 
-    # Copy feature folders (only files, preserve existing files in AIO)
+    # Copy feature folders (only files, preserve existing files in AIO).
+    # Shader files are excluded - copy_shaders.stamp owns the Shaders/ subdir
+    # so the two custom-build rules don't race on the same destinations.
     foreach(_fpath IN LISTS FEATURE_PATHS)
         if(EXISTS "${_fpath}")
             file(
@@ -474,6 +491,7 @@ if(AUTO_PLUGIN_DEPLOYMENT OR AIO_ZIP_TO_DIST)
                 LIST_DIRECTORIES FALSE
                 "${_fpath}/*"
             )
+            list(FILTER _feature_files EXCLUDE REGEX "/Shaders/")
             append_copy_if_different(_prepare_aio_cmds _feature_files "${_fpath}" "${AIO_DIR}")
         endif()
     endforeach()
@@ -906,7 +924,7 @@ if(AIO_ZIP_TO_DIST)
         COMMAND ${CMAKE_COMMAND} -E tar cf ${AIO_ARCHIVE} --format=7zip -- .
         COMMAND ${CMAKE_COMMAND} -E touch ${AIO_ZIP_STAMP}
         WORKING_DIRECTORY ${AIO_DIR}
-        DEPENDS PREPARE_AIO
+        DEPENDS PREPARE_AIO ${CMAKE_CURRENT_BINARY_DIR}/copy_shaders.stamp
         COMMENT "Creating AIO archive ${AIO_ARCHIVE}"
     )