The LSA file for reproduct ? And try with HTML too.

Please attach your survey, preferably as .lsa file.
It looks like you have debug mode activated in your config.php - can you deactivate it and see if you still get the error?

Please give feedback ASAP.

I have activated the debug mode on my demand for debug purposes.

Yes, I assumed that. Can you please anwer my question?

1) LSA file uploaded
2) With debug mode off the result still the same

3) HTML output issue 10569
https://bugs.limesurvey.org/view.php?id=10569

1) upgrade to 2.50+ (build 160223)
2) the problem remains in statistics
3) in the "Export results" feature the same message "TCPDF ERROR: Some data has already been output, can't send PDF file"
4) When "Printing answers" i get no PDF file and the warning "file_get_contents(/startpage.pstpl): failed to open stream: No such file or directory"

Note: upload another file whith the output of the warning in 4

Hi,

Please : test with a core template.
Maybe a white space in your config.php after the last ?> , maybe a plugin with same issue.
Actually : i can not impport your lsa : Carsten : it work for you ?
There are space before PK inforation.

Then it's surely a space somewhere in your installation : config.php or an external plugin.

I agree to Denis' analysis.
There must be somethin wrong with your installation. You should re-install LimeSurvey from scratch - also make sure that when you upload the files to your webserver use the binary mode, so files won't get changed.
Can you try and let us know if that helped?

I also added a fixed version of your .lsa file

I also cannot reproduce the problem using the fixed lsa file.

I have re-instaled LimeSurvey from scratch and now is OK, thank you very much for all the help