The following file structure produces the following error.
This file structure is reasonable and my project is an example.

_E:\
 |_folder_20char_step01
   |_folder_20char_step02
     |_folder_20char_step03
       |_folder_20char_step04
         |_folder_20char_step05
           |_folder_20char_step06
             |_solution_20char_1234
               |_solution_20char_1234.pro
               |_project_20char_12345
                 |_project_20char_12345.pro
                 |_file_20char_1234.cpp

22:01:14: Running steps for project solution_20char_1234...
22:01:14: Configuration unchanged, skipping qmake step.
22:01:14: Starting: "C:\Qt\Qt5.5.0\Tools\QtCreator\bin\jom.exe"
cd project_20char_12345\ && ( if not exist Makefile C:\Qt\Qt5.5.0\5.5\msvc2013\bin\qmake.exe E:\folder_20char_step01\folder_20char_step02\folder_20char_step03\folder_20char_step04\folder_20char_step05\folder_20char_step06\solution_20char_1234\project_20char_12345\project_20char_12345.pro -spec win32-msvc2013 "CONFIG+=debug" -o Makefile ) && C:\Qt\Qt5.5.0\Tools\QtCreator\bin\jom.exe -f Makefile
C:\Qt\Qt5.5.0\Tools\QtCreator\bin\jom.exe -f Makefile.Debug

Error: dependent '..\..\solution_20char_1234\project_20char_12345\file_20char_1234.cpp' does not exist.

jom: E:\folder_20char_step01\folder_20char_step02\folder_20char_step03\folder_20char_step04\folder_20char_step05\folder_20char_step06\build-solution_20char_1234-Desktop_Qt_5_5_0_MSVC2013_32bit-Debug\project_20char_12345\Makefile [debug] Error 2
jom: E:\folder_20char_step01\folder_20char_step02\folder_20char_step03\folder_20char_step04\folder_20char_step05\folder_20char_step06\build-solution_20char_1234-Desktop_Qt_5_5_0_MSVC2013_32bit-Debug\Makefile [sub-project_20char_12345-make_first-ordered] Error 2
22:01:14: The process "C:\Qt\Qt5.5.0\Tools\QtCreator\bin\jom.exe" exited with code 2.
Error while building/deploying project solution_20char_1234 (kit: Desktop Qt 5.5.0 MSVC2013 32bit)
When executing step "Make"
22:01:14: Elapsed time: 00:00.