View source for FAQ/Troubleshooting

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[[Category:FAQSection]]

== FAQ Section [[faqnumber::8]]: [[faqname::Troubleshooting]] ==
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[[faqdescription::Figuring out what went wrong]]
=== An application ends with a ''segmentation fault''. What is wrong? ===

A segmentation fault usually occurs when a program tries to access memory outside its bounds (see [http://en.wikipedia.org/wiki/Segmentation_Fault Segmentation Fault on Wikipedia]). In OpenFOAM this usually occurs when a <tt>List<></tt> or similar is accessed with an index outside of the allocated domain. To find out where this occurs see make a separate copy of the OF-sources, recompile them with the switch <tt>WM_COMPILE_OPTION</tt> set to Debug (just uncomment the right lines in the {{tt|bashrc/cshrc}} files). This makes OF run slower, but accesses to <tt>List<></tt> etc are checked for ranges and the program aborts if you access outside of a range (plus you get a stack trace). This won't solve your problem, but it will help you find out where it occurs.

See also [[HowTo_debugging|General debugging tips]]. For recompiling OpenFOAM look at [[Installation]] (specially page [[Installation/Working_with_the_Shell]]) or the older page [[Howto_compile_OpenFOAM]].

=== My program stops with an output that starts with <tt>#0 Foam::error::printStack(Foam::Ostream&)</tt> ===

You encountered a program error. Upon hitting that error OpenFOAM produced a stack trace (a list of the functions that were called) which is very useful to find the location at which the problem occured. It is possible to get that stack-trace with the source files and the line numbers of the functions which might help to find out what the problem is. To do so you have to [[Howto_compile_OpenFOAM#Modifications_for_a_debug_version_of_OpenFOAM|compile a debug version of OpenFOAM]]. (see also the ''segmentation fault''-question above)

=== I'm unable to reproduce a crash. What's going on? ===
If you run the same exact simulation twice or more times, but there is an occasional crash in different places, then there are a few possibilities:
* There could be a numerical instability in the calculations. This could be due to the compiler options used (such as {{tt|--fast-math}}).
* There could be some randomness introduced somewhere by a pseudo-random number generator. This is common in the particle/chemical type solvers in OpenFOAM.
* There could be a hardware problem. In this case, check this page: [[HowTo Check if RAM and CPU are OK|How to Check if RAM and CPU are OK]]

=== Cannot open script file? ===
; Symptom: The common error messages for this scenario are:
<pre>./Allwmake: 7: .: Can't open /wmake/scripts/AllwmakeParseArguments
./Allrun: 5: .: Can't open /bin/tools/RunFunctions
</pre>

; Reason and solution: The OpenFOAM environment is not properly activated. For more details, read [[Installation/Working_with_the_Shell]].

=== Cannot use the <tt>-fields</tt> option in <tt>foamToVTK</tt>? ===

; Symptom: Using the following command:
: <bash>foamToVTK -fields p</bash>
: gives the following (somewhat) cryptic error message:
<dd><pre>--> FOAM FATAL IO ERROR:
incorrect first token, expected <int> or '(', found on line 0 the word 'p'</pre></dd>

; Solution: As listed in [[foamToVTK]], the help message states: the following:
<dd><pre>-fields <wordList>
                   only convert the specified fields - eg '(p T U)'
</pre></dd>
: this means that the complete list structure needs to be used, including quotes and parenthesis:
: <bash>foamToVTK -fields '(p)'</bash>
: because the parenthesis are needed for the list that OpenFOAM was complaining that it wasn't finding and the quotes are needed for the shell to not think that this was a [http://www.tldp.org/LDP/abs/html/subshells.html sub-shell request].

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Faqdescription	Figuring out what went wrong +
Faqname	Troubleshooting +
Faqnumber	8 +