# undefined symbol: PyExc\_ValueError
**URL:** https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494
**Category:** In Situ Support
**Created:** [October 5, 2020, 8:18am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494 "2020-10-05T08:18:16Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@zhe](https://discourse.paraview.org/u/zhe)
#### Post date: [October 5, 2020, 8:18am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/1 "2020-10-05T08:18:16Z")
Hello,
I tried to build a program based on the Catalyst, the paraview and my program is ok to compile, but I got this error when I run the program:
```auto
./example/MandelbulbCatalystExample/MandelbulbDynamic: symbol lookup error: /home/zw241/cworkspace/build/build_paraview/lib64/libvtkWrappingPythonCore-pv5.8.so.1: undefined symbol: PyExc_ValueError
```
Then I tried to use the nm command to check the .so file:
```auto
$ nm /home/zw241/cworkspace/build/build_paraview/lib64/libvtkWrappingPythonCore-pv5.8.so.1 > nmresults.txt
$ cat nmresults.txt |grep PyExc_ValueError
U PyExc_ValueError
$ cat nmresults.txt |grep Py
U PyArg_ParseTuple
U PyArg_UnpackTuple
U PyBaseObject_Type
U PyBool_FromLong
U PyBool_Type
U PyBuffer_FillContiguousStrides
U PyBuffer_FillInfo
U PyBuffer_Release
U PyByteArray_Type
U PyBytes_AsString
U PyBytes_AsStringAndSize
U PyBytes_FromStringAndSize
U PyBytes_Size
U PyCFunction_NewEx
U PyCallable_Check
U PyDict_GetItem
U PyDict_New
...
```
It looks that PyExc\_ValueError and some other necessary python type are not defined, and I am curious about this, I have enabled the paraview Catalyst when I built the paraview
```auto
$ cat CMakeCache.txt |grep Catalyst
Catalyst_LIB_DEPENDS:STATIC=general;VTK::CommonCore;general;ParaView::RemotingApplication;general;VTK::FiltersGeneral;general;VTK::vtksys;general;VTK::ParallelMPI;
PythonCatalyst_LIB_DEPENDS:STATIC=general;ParaView::Catalyst;general;VTK::PythonInterpreter;general;ParaView::PythonInitializer;general;VTK::ParallelCore;
//Enable the ParaView::Catalyst module.
VTK_MODULE_ENABLE_ParaView_Catalyst:STRING=YES
//Enable the ParaView::PythonCatalyst module.
VTK_MODULE_ENABLE_ParaView_PythonCatalyst:STRING=YES
//Enable the ParaView::RemotingLive module. Catalyst LIVE
vtkPVCatalystPython_LIB_DEPENDS:STATIC=general;ParaView::Catalyst;general;VTK::WrappingPythonCore;
vtkPVPythonCatalystPython_LIB_DEPENDS:STATIC=general;ParaView::PythonCatalyst;general;VTK::WrappingPythonCore;
//ADVANCED property for variable: VTK_MODULE_ENABLE_ParaView_Catalyst
VTK_MODULE_ENABLE_ParaView_Catalyst-ADVANCED:INTERNAL=1
//MODIFIED property for variable: VTK_MODULE_ENABLE_ParaView_Catalyst
VTK_MODULE_ENABLE_ParaView_Catalyst-MODIFIED:INTERNAL=ON
//STRINGS property for variable: VTK_MODULE_ENABLE_ParaView_Catalyst
VTK_MODULE_ENABLE_ParaView_Catalyst-STRINGS:INTERNAL=YES;WANT;DONT_WANT;NO;DEFAULT
//ADVANCED property for variable: VTK_MODULE_ENABLE_ParaView_PythonCatalyst
VTK_MODULE_ENABLE_ParaView_PythonCatalyst-ADVANCED:INTERNAL=1
//MODIFIED property for variable: VTK_MODULE_ENABLE_ParaView_PythonCatalyst
VTK_MODULE_ENABLE_ParaView_PythonCatalyst-MODIFIED:INTERNAL=ON
//STRINGS property for variable: VTK_MODULE_ENABLE_ParaView_PythonCatalyst
VTK_MODULE_ENABLE_ParaView_PythonCatalyst-STRINGS:INTERNAL=YES;WANT;DONT_WANT;NO;DEFAULT
```
This is the Python3 info in CMakeCache
```auto
$ cat CMakeCache.txt |grep Python3
Python3_LIBRARY_DEBUG:FILEPATH=
Python3_LIBRARY_RELEASE:FILEPATH=/projects/community/python/3.8.5/gc563/lib/libpython3.8.a
_Python3_EXECUTABLE:FILEPATH=/projects/community/python/3.8.5/gc563/bin/python3.8
_Python3_INCLUDE_DIR:PATH=/projects/community/python/3.8.5/gc563/include/python3.8
_Python3_LIBRARY_RELEASE:FILEPATH=/projects/community/python/3.8.5/gc563/lib/libpython3.8.a
//Details about finding Python3
FIND_PACKAGE_MESSAGE_DETAILS_Python3:INTERNAL=[/projects/community/python/3.8.5/gc563/lib/libpython3.8.a][/projects/community/python/3.8.5/gc563/include/python3.8][cfound components: Development][v3.8(3.2)]
//ADVANCED property for variable: Python3_LIBRARY_DEBUG
Python3_LIBRARY_DEBUG-ADVANCED:INTERNAL=1
//MODIFIED property for variable: Python3_LIBRARY_DEBUG
Python3_LIBRARY_DEBUG-MODIFIED:INTERNAL=ON
//ADVANCED property for variable: Python3_LIBRARY_RELEASE
Python3_LIBRARY_RELEASE-ADVANCED:INTERNAL=1
_Python3_DEVELOPMENT_SIGNATURE:INTERNAL=e2eb5da72d168ff534301bea65f0cb00
//ADVANCED property for variable: _Python3_EXECUTABLE
_Python3_EXECUTABLE-ADVANCED:INTERNAL=1
//ADVANCED property for variable: _Python3_INCLUDE_DIR
_Python3_INCLUDE_DIR-ADVANCED:INTERNAL=1
_Python3_INTERPRETER_SIGNATURE:INTERNAL=4f8d5e5cc14b6010189102c56249c7e7
//ADVANCED property for variable: _Python3_LI
```
I also got the similar errors when I execute the pvbatch or pvpython:
```auto
$ ./pvbatch
./pvbatch: symbol lookup error: /cache/home/zw241/cworkspace/build/build_paraview/install/bin/../lib64/libvtkWrappingPythonCore-pv5.8.so.1: undefined symbol: PyExc_ValueError
$ ./pvpython
./pvpython: symbol lookup error: /cache/home/zw241/cworkspace/build/build_paraview/install/bin/../lib64/libvtkWrappingPythonCore-pv5.8.so.1: undefined symbol: PyExc_ValueError
```
Thanks a lot for your help!
---
### Author:  [@zhe](https://discourse.paraview.org/u/zhe)
#### Post date: [October 6, 2020, 2:35am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/2 "2020-10-06T02:35:59Z")
It looks that this problem is similar with this one ([Building Paraview from source is missing pvbatch](https://discourse.paraview.org/t/building-paraview-from-source-is-missing-pvbatch/5050)), but I’m still not sure the reason for this case since it seems that the python path looks good
---
### Author:  [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [October 6, 2020, 1:06pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/3 "2020-10-06T13:06:31Z")
You can rebuild ParaView with `VTK_PYTHON_OPTIONAL_LINK=OFF` to force libpython linking from libraries. We try to detect whether we need to do this, though it may have been fixed properly after 5.8. Are you using a 5.8.x release or `master`?
---
### Author:  [@utkarsh.ayachit](https://discourse.paraview.org/u/utkarsh.ayachit)
#### Post date: [October 6, 2020, 1:24pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/4 "2020-10-06T13:24:33Z")
@ben.boeckel, what’s the reason to have `VTK_PYTHON_OPTIONAL_LINK` ON by default? Seems it me it’s only needed for wheels, in which case shouldn’t we only turn it ON when building wheels alone?
---
### Author:  [@zhe](https://discourse.paraview.org/u/zhe)
#### Post date: [October 6, 2020, 1:35pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/5 "2020-10-06T13:35:24Z")
Thanks l lot for your help! I use the version 5.8.0, does that because the python library is .a file? so I need to force it to be linked, if it is .so, we will not care about it?
I got some error like this when I set VTK\_PYTHON\_OPTIONAL\_LINK as OFF:
```auto
/usr/bin/ld: /projects/community/python/3.8.5/gc563/lib/libpython3.8.a(abstract.o): relocation R_X86_64_32S against symbol `_Py_NotImplementedStruct' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /projects/community/python/3.8.5/gc563/lib/libpython3.8.a(boolobject.o): relocation R_X86_64_32S against symbol `_Py_FalseStruct' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /projects/community/python/3.8.5/gc563/lib/libpython3.8.a(bytearrayobject.o): relocation R_X86_64_32 against symbol `_PyByteArray_empty_string' can not be used when making a shared object; recompile with -fPIC
...
```
maybe it is the problem of the python3 on this cluster, do i need to rebuild a python3 with --enable-shared?
---
### Author:  [@zhe](https://discourse.paraview.org/u/zhe)
#### Post date: [October 6, 2020, 2:00pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/6 "2020-10-06T14:00:51Z")
BTW, for the VTK/Wrapping/PythonCore in 5.8.0, it looks that there is typo about “PYTHON\_VERSION\_MAJOR” and PYTHON\_MAJOR\_VERSION" maybe this is fixed in the latest version.
---
### Author:  [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [October 6, 2020, 2:45pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/7 "2020-10-06T14:45:52Z")
Ah, you have a static Python. We should also force it off there.
As for your linking errors, your Python isn’t built with `-fPIC`, so you’ll need another Python to use any shared libraries with it.
And indeed that’s a typo. Thanks for pointing it out.
---
### Author:  [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [October 6, 2020, 2:51pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/8 "2020-10-06T14:51:38Z")
It’s also needed for Anaconda. I don’t know about other Python distributions.
---
### Author:  [@zhe](https://discourse.paraview.org/u/zhe)
#### Post date: [October 7, 2020, 2:09am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/9 "2020-10-07T02:09:43Z")
Thanks a lot for your help!
---
### Author:  [@ihar](https://discourse.paraview.org/u/ihar)
#### Post date: [March 11, 2021, 10:13am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/10 "2021-03-11T10:13:48Z")
Had similar issue, `VTK_PYTHON_OPTIONAL_LINK=OFF` flag solved the problem. Thank you.
---
### Author:  [@olesenm](https://discourse.paraview.org/u/olesenm)
#### Post date: [July 23, 2021, 11:21am UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/11 "2021-07-23T11:21:07Z")
Now hitting the same problem (with PV 5.9.1). I can solve it by adding in `libcatalyst` as a link dependency or forcibly loading libpython in my application. Neither of these seems quite right.
The new version has a ParaView::vtkcatalyst module, but that does not seem to do it either.
Quick tips?
---
### Author:  [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [July 23, 2021, 6:07pm UTC](https://discourse.paraview.org/t/undefined-symbol-pyexc-valueerror/5494/12 "2021-07-23T18:07:39Z")
Where are you getting the linker errors? In your application linking to ParaView libraries? If that’s the case, I would just use the `VTK::Python` target here for now. I _think_ this has been fixed on `master`, at least for Catalyst2 though.