The cause of the problem is a ‘SPACE’ at the beginning of a unknown module script.
- Find the script causing this problem:
grep -n -o -R \ \<\?php * |grep :1:
- Delete ‘SPACE’ at the beginning of the found script
- Delete Cache
Here is another way of using grep to find the culprit. Mostly it is module file so…
grep -R -H '^ <?php' modules/**/*.module
This will check all module files withing your module folder ( i am a step back in my sites/all folder in my linux terminal to find culprit.)
If you find two spaces leave two space between ^ and <?php, if one space leave one.
you will get the path of file which is culprit.