# MCNPY Exception: Error importing MCNP Deck from file **URL:** \ **Category:** User Support\ **Created:** [June 5, 2024, 7:33pm UTC](https://openmc.discourse.group/t/mcnpy-exception-error-importing-mcnp-deck-from-file/4354 "2024-06-05T19:33:43Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![ron](https://avatars.discourse-cdn.com/v4/letter/r/ecae2f/32.png) [@ron](https://openmc.discourse.group/u/ron)\ **Post date:** [June 5, 2024, 7:33pm UTC](https://openmc.discourse.group/t/mcnpy-exception-error-importing-mcnp-deck-from-file/4354/1 "2024-06-05T19:33:43Z")
To all: I’m getting this error: Exception: Error importing MCNP Deck from file: my\_file\_name Note: I am running the script in Anaconda-Navigator Jupyter I am running the following: Windows11 Pro WSL2 Ubuntu 22.04.4 LTS Conda version 24.5.0 Python version 3.11.0 final.0 solver : libmamba (default) virtual packages : \_\_archspec=1=skylake \_\_conda=24.5.0=0 \_\_cuda=12.3=0 \_\_glibc=2.35=0 \_\_linux=5.15.146.1=0 \_\_unix=0=0 (PySide6. **version** ) 6.7.0 (PySide6.QtCore. **version** ) 6.7.0 from PyQt6 import QtCore 6.7.0 from PyQt5 import QtCore 5.15.8 numpy.version.version 1.26.4 matplotlib 3.8.4 I am trying to import and convert an MCNP (LANL) input file to OpenMC, using MCNPY. The input file is a simple sphere filled with water, a monoenergetic photon source, and a single tally. I’ve verified that the file will run without errors on MCNP6.3. This is the script I am using. Note that It contains the MCNP6.3 input file as an output. import mcnpy as mp %matplotlib inline from math import pi, sin, cos import numpy as np import openmc import os from openmc\_source\_plotter import plot\_source\_position home = (os.environ[‘HOME’]) # I tried this both ways. I get the same error # mcnp\_file\_path = “/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp” mcnp\_file\_path = home + “/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp” # I tried this both ways. Same error. # file\_path = “/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp” file\_path = mcnp\_file\_path if os.path.exists(file\_path): print(“The file exists!”) else: print(“The file does not exist.”) # This is a listing of the simple input file. I verified that it runs with MCNP6.3 !cat “/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp” $ c title simple input for mcnpy conversion c 10 1 -1.0 -10 imp:p=1 90 0 10 imp:p=0 10 so 50 mode p c m1 1000. 0.667 8000. 0.333 c sdef par=2 erg=1 c f2:p 10 c nps 1e6 # I tried this both ways - I get the same error # deck = mp.Deck.read(“/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp”) deck = mp.Deck.read(mcnp\_file\_path) This is the full error printout: * * * Py4JJavaError Traceback (most recent call last) File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/metapy/gateway.py:37, in load\_file(filename) 36 try: —\> 37 return gateway.loadFileMcnp(filename) 38 except: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/java\_gateway.py:1322, in JavaMember. **call** (self, \*args) 1321 answer = self.gateway\_client.send\_command(command) → 1322 return\_value = get\_return\_value( 1323 answer, self.gateway\_client, self.target\_id, self.name) 1325 for temp\_arg in temp\_args: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/protocol.py:326, in get\_return\_value(answer, gateway\_client, target\_id, name) 325 if answer[1] == REFERENCE\_TYPE: → 326 raise Py4JJavaError( 327 “An error occurred while calling {0}{1}{2}.\n”. 328 format(target\_id, “.”, name), value) 329 else: Py4JJavaError: An error occurred while calling t.loadFileMcnp. : java.lang.NoClassDefFoundError: org/junit/Assert at org.eclipse.xtext.testing.validation.ValidationTestHelper.assertNoErrors(ValidationTestHelper.java:186) at org.eclipse.xtext.testing.validation.ValidationTestHelper.assertNoErrors(ValidationTestHelper.java:92) at EntryPoint.loadFileMcnp(EntryPoint.java:123) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244) at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357) at py4j.Gateway.invoke(Gateway.java:282) at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132) at py4j.commands.CallCommand.execute(CallCommand.java:79) at py4j.GatewayConnection.run(GatewayConnection.java:238) at java.base/java.lang.Thread.run(Thread.java:829) Caused by: java.lang.ClassNotFoundException: org.junit.Assert at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581) at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:527) … 14 more During handling of the above exception, another exception occurred: AttributeError Traceback (most recent call last) File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/metapy/gateway.py:40, in load\_file(filename) 39 try: —\> 40 return gateway.loadFileSerpent(filename) 41 except: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/java\_gateway.py:1322, in JavaMember. **call** (self, \*args) 1321 answer = self.gateway\_client.send\_command(command) → 1322 return\_value = get\_return\_value( 1323 answer, self.gateway\_client, self.target\_id, self.name) 1325 for temp\_arg in temp\_args: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/protocol.py:326, in get\_return\_value(answer, gateway\_client, target\_id, name) 325 if answer[1] == REFERENCE\_TYPE: → 326 raise Py4JJavaError( 327 “An error occurred while calling {0}{1}{2}.\n”. 328 format(target\_id, “.”, name), value) 329 else: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/protocol.py:467, in Py4JJavaError. **init** (self, msg, java\_exception) 465 self.java\_exception = java\_exception 466 self.exception\_cmd = EXCEPTION\_COMMAND\_NAME + REFERENCE\_TYPE + → 467 java\_exception.\_target\_id + “\n” + END\_COMMAND\_PART AttributeError: ‘Deck’ object has no attribute ‘\_target\_id’ During handling of the above exception, another exception occurred: AttributeError Traceback (most recent call last) File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/metapy/gateway.py:43, in load\_file(filename) 42 try: —\> 43 return gateway.loadFileKeno(filename) 44 except: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/java\_gateway.py:1322, in JavaMember. **call** (self, \*args) 1321 answer = self.gateway\_client.send\_command(command) → 1322 return\_value = get\_return\_value( 1323 answer, self.gateway\_client, self.target\_id, self.name) 1325 for temp\_arg in temp\_args: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/protocol.py:326, in get\_return\_value(answer, gateway\_client, target\_id, name) 325 if answer[1] == REFERENCE\_TYPE: → 326 raise Py4JJavaError( 327 “An error occurred while calling {0}{1}{2}.\n”. 328 format(target\_id, “.”, name), value) 329 else: File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/py4j/protocol.py:467, in Py4JJavaError. **init** (self, msg, java\_exception) 465 self.java\_exception = java\_exception 466 self.exception\_cmd = EXCEPTION\_COMMAND\_NAME + REFERENCE\_TYPE + → 467 java\_exception.\_target\_id + “\n” + END\_COMMAND\_PART AttributeError: ‘Deck’ object has no attribute ‘\_target\_id’ During handling of the above exception, another exception occurred: Exception Traceback (most recent call last) File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/mcnpy/deck.py:264, in Deck.\_read(self, filename, renumber, preprocess) 263 filename = preprocessor(filename) → 264 inp = load\_file(filename) 265 self.\_deck = inp File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/metapy/gateway.py:45, in load\_file(filename) 44 except: —\> 45 raise Exception('PARSING ERROR! for file: ’ + filename) Exception: PARSING ERROR! for file: /home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp During handling of the above exception, another exception occurred: Exception Traceback (most recent call last) Cell In[5], line 3 1 # I tried this both ways - I get the same error 2 # deck = mp.Deck.read(“/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp”) ----\> 3 deck = mp.Deck.read(mcnp\_file\_path) File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/mcnpy/deck.py:255, in Deck.read(cls, filename, renumber, preprocess) 252 @classmethod 253 def read(cls, filename=‘inp.mcnp’, renumber=False, preprocess=False): 254 \_deck = Deck() → 255 \_deck.\_read(filename, renumber, preprocess) 256 return \_deck File ~/anaconda3/envs/openmc-env/lib/python3.12/site-packages/mcnpy/deck.py:279, in Deck.\_read(self, filename, renumber, preprocess) 277 self.\_deck = filename 278 else: → 279 raise Exception(‘Error importing MCNP Deck from file "’ + filename 280 + ‘"’) 281 try: 282 cells = self.\_deck.cells.cells Exception: Error importing MCNP Deck from file “/home/rlavera/ipynb/mcnpy-examples/room-conv/mcnpy-conv.mcnp” ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [June 6, 2024, 12:43am UTC](https://openmc.discourse.group/t/mcnpy-exception-error-importing-mcnp-deck-from-file/4354/2 "2024-06-06T00:43:58Z")
I can’t comment on the mcnpy error, but I would suggest trying out [`openmc_mcnp_adapter`](https://github.com/openmc-dev/openmc_mcnp_adapter/) which has been used to successfully convert very complicated MCNP models. ---
**Author:** ![ron](https://avatars.discourse-cdn.com/v4/letter/r/ecae2f/32.png) [@ron](https://openmc.discourse.group/u/ron)\ **Post date:** [June 6, 2024, 3:22pm UTC](https://openmc.discourse.group/t/mcnpy-exception-error-importing-mcnp-deck-from-file/4354/3 "2024-06-06T15:22:03Z")
Paul I’d seen this app before. I didn’t install it before bc of some of the stated limitations (SDEF etc.) I may need to take a look at it again. Thanks Ron ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [June 6, 2024, 8:53pm UTC](https://openmc.discourse.group/t/mcnpy-exception-error-importing-mcnp-deck-from-file/4354/4 "2024-06-06T20:53:15Z")
As far as I’m aware, I don’t think mcnpy will handle `sdef` cards for you either. MCNP and OpenMC don’t have a completely interchangeable system for defining sources (some MCNP features are not available in OpenMC and vice versa). So, the source definition you may have to handle yourself.