Quick answer: Quoting myself from two previous posts:

1. Quote:

   Originally Posted by wyldckat (Post 550182) Not enough information. Please follow the instructions given on this thread: http://www.cfd-online.com/Forums/ope...-get-help.html

2. Quote:

   Originally Posted by wyldckat (Post 467606) [...] this is a frequently asked question, I've added to the FAQ: http://openfoamwiki.net/index.php/FA..._invalid.22.3F

And please do keep in mind that we cannot see what you do not show us, nor can we see what you do not share with us. Because that error message alone can mean several things, depending on the exact context.

I ran into this error today and have been tinkering with it. None of my OF utilities were working and all threw the same error so I thought I had a messed up build. But eventually I found it was just a space in a folder name.

As mentioned in the above threads, Directory and Mesh file names which are irregular (contains underscore, other symbols) are poisonous. I too was down with this problem. Changed all my file names and case directory names as simple Numbers and Characters

dear mark,
I'm quite out of space in my ssd disk of my laptop by now. So I would often have the need to try/run/visualize some cases on an external USB I have, but which unfortunately is recognized as TOSHIBA EXT by the system, with a whitespace in the name! Is this possible modifying some files as fileName.H to make OF digest these names strings?

Quick answer: You can try using symbolic links. For example, if you run:
it will:

1. Create
2. and go into the default folder that OpenFOAM assigns to the user for running cases inside;
3. and then creates a symbolic link path to the USB disk.

I'm assuming you are using Ubuntu, therefore you need to change the "username" word with your own user-name.

Using quotes for the path with spaces is necessary. The alternative would be to use the backslash:
Once the symbolic link is created, you can now go into the symbolic folder:
and then navigate to the folder where you have the cases from there onwards.

Note: You don't need to delete the symbolic link when you safely eject the USB disk.

Just in case, it may help someone.
I had the same problem but in my case I had a jupyter notebook file saved at the simulation case folder, with a space in its name "notebook name.ipynb". This was enough to break the reconstructPar command.

Quick question @RK_Token: Which OpenFOAM version were/are you using?

I ask this because if it's one of the more recent versions, we can still have this fixed much sooner than later.

And I am very glad that Python based Jupyter Notebooks are being used along with OpenFOAM!

Hey @wyldckat I'm using OpenFOAM-4.1 64bit

If you need more information let me know.

You may want to make a backup and copied some file then renamed it. and there is a space in the name of your execution file.

I also meet this problem just now.

I make a new folder and then copy all the inner files into this. And it worked.

FWIW this longstanding problem has now been fixed in the upcoming OpenFOAM-v1712 release. Now the POSIX readDir will silently (or noisily) drop file and directory names with weird characters that would cause OpenFOAM problems.

Hello!
I faced a similar issue and solved it successfully.
>>
Create databases as time
fileName::stripInvalid() called for invalid fileName 02vectorvelmag.png
For debug level (= 2) > 1 this is considered fatal
Aborted (core dumped)
>>
Solution>>>>>
the file name "02vectorvelmag.png" is actually a .png file saved in my caseDirectory which is actually named as "02 vector vel mag.png" which I saved during post-processing of another case.
So, I removed this file to another location and run the intended command once again. it worked.

That solved my problem. Thank you!
I had one space in my directory name.

I had this mistake and found that I had made a backup copy of system and called it system.copy. That gave the error invalidFileName systemcopy

Perhaps it's something as simple as an extra file or directory in you setup folders.

Maybe useful for someone. I met the similar error, i.e.

for time = 0LUID_inner
fileName::stripInvalid() called for invalid fileName FLUID_inner
For debug level (= 2) > 1 this is considered fatal

when I run the case from Allrun script. But it run without this error if I input the same command in terminal. Finally I find there are two blank lines after the command which the above error emit. After delete these two blank lines, it runs successfully.

I am new and not sure if you have already know this.