Upgrade fails: to 2.3.7

[Rich Shepard]

Trying to upgrade from 2.3.6.1 to 2.3.7 fails here:
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make[5]: Entering directory '/tmp/SBo/lyx-2.3.7/src/support'
   CXX      FileMonitor.o
In file included from FileMonitor.cpp:262:0:
moc_FileMonitor.cpp:13:2: error: #error "This file was generated using the moc from 4.8.7. It"
  #error "This file was generated using the moc from 4.8.7. It"
   ^
moc_FileMonitor.cpp:14:2: error: #error "cannot be used with the include files from this version of Qt."
  #error "cannot be used with the include files from this version of Qt."
   ^
moc_FileMonitor.cpp:15:2: error: #error "(The moc has changed too much.)"
  #error "(The moc has changed too much.)"
   ^
moc_FileMonitor.cpp:64:7: error: ‘QMetaObjectExtraData’ does not name a type
  const QMetaObjectExtraData lyx::support::FileMonitorGuard::staticMetaObjectExtraData = {
        ^
moc_FileMonitor.cpp:70:53: error: ‘staticMetaObjectExtraData’ was not declared in this scope
        qt_meta_data_lyx__support__FileMonitorGuard, &staticMetaObjectExtraData }
                                                      ^
moc_FileMonitor.cpp: In member function ‘virtual const QMetaObject* lyx::support::FileMonitorGuard::metaObject() const’:
moc_FileMonitor.cpp:79:71: error: conditional expression between distinct pointer types ‘QDynamicMetaObjectData*’ and ‘const QMetaObject*’ lacks a cast
      return QObject::d_ptr->metaObject ? QObject::d_ptr->metaObject : &staticMetaObject;
                                                                        ^
moc_FileMonitor.cpp: At global scope:
moc_FileMonitor.cpp:152:7: error: ‘QMetaObjectExtraData’ does not name a type
  const QMetaObjectExtraData lyx::support::FileMonitor::staticMetaObjectExtraData = {
        ^
moc_FileMonitor.cpp:158:48: error: ‘staticMetaObjectExtraData’ was not declared in this scope
        qt_meta_data_lyx__support__FileMonitor, &staticMetaObjectExtraData }
                                                 ^
moc_FileMonitor.cpp: In member function ‘virtual const QMetaObject* lyx::support::FileMonitor::metaObject() const’:
moc_FileMonitor.cpp:167:71: error: conditional expression between distinct pointer types ‘QDynamicMetaObjectData*’ and ‘const QMetaObject*’ lacks a cast
      return QObject::d_ptr->metaObject ? QObject::d_ptr->metaObject : &staticMetaObject;
                                                                        ^
moc_FileMonitor.cpp: At global scope:
moc_FileMonitor.cpp:239:7: error: ‘QMetaObjectExtraData’ does not name a type
  const QMetaObjectExtraData lyx::support::ActiveFileMonitor::staticMetaObjectExtraData = {
        ^
moc_FileMonitor.cpp:245:54: error: ‘staticMetaObjectExtraData’ was not declared in this scope
        qt_meta_data_lyx__support__ActiveFileMonitor, &staticMetaObjectExtraData }
                                                       ^
moc_FileMonitor.cpp: In member function ‘virtual const QMetaObject* lyx::support::ActiveFileMonitor::metaObject() const’:
moc_FileMonitor.cpp:254:71: error: conditional expression between distinct pointer types ‘QDynamicMetaObjectData*’ and ‘const QMetaObject*’ lacks a cast
      return QObject::d_ptr->metaObject ? QObject::d_ptr->metaObject : &staticMetaObject;
                                                                        ^
Makefile:977: recipe for target 'FileMonitor.o' failed
make[5]: *** [FileMonitor.o] Error 1
make[5]: Leaving directory '/tmp/SBo/lyx-2.3.7/src/support'
Makefile:828: recipe for target 'all' failed
make[4]: *** [all] Error 2
make[4]: Leaving directory '/tmp/SBo/lyx-2.3.7/src/support'
Makefile:2806: recipe for target 'all-recursive' failed
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory '/tmp/SBo/lyx-2.3.7/src'
Makefile:1900: recipe for target 'all' failed
make[2]: *** [all] Error 2
make[2]: Leaving directory '/tmp/SBo/lyx-2.3.7/src'
Makefile:579: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/tmp/SBo/lyx-2.3.7'
Makefile:474: recipe for target 'all' failed
make: *** [all] Error 2
-----

Installed here are:
qt-4.8.7-x86_64-4
qt-compat32-4.8.7-x86_64-4compat32
qt-creator-4.12.3-x86_64-1_SBo
qt-gstreamer-1.2.0-x86_64-1
qt5-5.12.8-x86_64-1_SBo
qt5-webkit-5.212.0_alpha4-x86_64-3_SBo
qt5ct-1.1-x86_64-1_SBo

What am I missing?

TIA,

Rich