Cannot reproduce, please write steps how to reproduce. How did you saved only chart?

Simple:

Step 1:  Write a column with text and other with numbers
Step 2:  Select two column with data
Step 3:  Click on the icon Chart and select a type of chart's
Step 4:  Click on File -> Save and type a name for it
Step 5: Click on File -> Exit LibreOffice
Your Chart is saved, but your Sheets and your data are lost

Suggestion: Change the name of Save for Save Chart, and when Exit Alert for Save this Sheet.

(In reply to raal from comment #1)
> Cannot reproduce, please write steps how to reproduce. How did you saved
> only chart?

Simple:
Step 1:  Write a column with text and other with numbers
Step 2:  Select two column with data
Step 3:  Click on the icon Chart and select a type of chart's
Step 4:  Click on File -> Save and type a name for it
Step 5: Click on File -> Exit LibreOffice
Your Chart is saved, but your Sheets and your data are lost

Suggestion: Change the name of Save for Save Chart, and when Exit Alert for Save this Sheet.

I can not confirm with LO Verze: 5.0.1.2
ID sestavení: 81898c9f5c0d43f3473ba111d7b351050be20261, win7

After Step 5: Click on File -> Exit LibreOffice -> message "do you want to save untitled.ods?"

Please test with version 5.0.1.2, http://www.libreoffice.org/download/

(In reply to raal from comment #4)
> I can not confirm with LO Verze: 5.0.1.2
> ID sestavení: 81898c9f5c0d43f3473ba111d7b351050be20261, win7
> 
> After Step 5: Click on File -> Exit LibreOffice -> message "do you want to
> save untitled.ods?"
> 
> Please test with version 5.0.1.2, http://www.libreoffice.org/download/

On weekend I is in my home, here I use Linux Ubuntu 15.04 and I am use L O Version: 5.0.1.2 Build ID: 00m0(Build:2) Locale: pt-BR (pt_BR.UTF-8) and the same error in step by step.
After Step 5: nothing... only the LO closed.

I did forget... Before the Step 1 I only open the L.O. with a default blank sheet.

(In reply to Edison Santos from comment #5)
> (In reply to raal from comment #4)
> > I can not confirm with LO Verze: 5.0.1.2
> > ID sestavení: 81898c9f5c0d43f3473ba111d7b351050be20261, win7
> > 
> > After Step 5: Click on File -> Exit LibreOffice -> message "do you want to
> > save untitled.ods?"
> > 
> > Please test with version 5.0.1.2, http://www.libreoffice.org/download/
> 
> On weekend I is in my home, here I use Linux Ubuntu 15.04 and I am use L O
> Version: 5.0.1.2 Build ID: 00m0(Build:2) Locale: pt-BR (pt_BR.UTF-8) and the
> same error in step by step.
> After Step 5: nothing... only the LO closed.

I do test with a spreadsheet with data and new problem found: in Step 4: Error saving the document spreadshet_test: Wrong parameter. The operation was started under an invalid parameter.
But after Step 5: the message really comes "do you want to save spreadsheet_test.ods?"

(In reply to Edison Santos from comment #7)
> (In reply to Edison Santos from comment #5)
> > (In reply to raal from comment #4)
> > > I can not confirm with LO Verze: 5.0.1.2
> > > ID sestavení: 81898c9f5c0d43f3473ba111d7b351050be20261, win7
> > > 
> > > After Step 5: Click on File -> Exit LibreOffice -> message "do you want to
> > > save untitled.ods?"
> > > 
> > > Please test with version 5.0.1.2, http://www.libreoffice.org/download/
> > 
> > On weekend I is in my home, here I use Linux Ubuntu 15.04 and I am use L O
> > Version: 5.0.1.2 Build ID: 00m0(Build:2) Locale: pt-BR (pt_BR.UTF-8) and the
> > same error in step by step.
> > After Step 5: nothing... only the LO closed.
> 
> I do test with a spreadsheet with data and new problem found: in Step 4:
> Error saving the document spreadshet_test: Wrong parameter. The operation
> was started under an invalid parameter.

This is probably another bug. If it is reproducible, please create new bug and attach test file with steps to reproduce.

> But after Step 5: the message really comes "do you want to save
> spreadsheet_test.ods?"

So works LO 5 as expected or not - comment 5 ? I've tested with new empty sheet too (comment 6). Please try to retest, we need reproducible steps, thanks