A TYPO3 4.3 project running nicely on my local development system did not produce the expected icons on the remote live server. It took me the better part of a day to find out why…
The problem did not affect all parts of the system, but only the output of one foreign extension (file_explorer) that I used in this project.
Both the local and the remote system were running Windows and Apache. As I could not use my development IDE on the remote server, debugging was very slow and I had to trace the problem through several classes of the extension down to the core of TYPO3.
Finally I found that the icons were in fact created but with a size of 0 bytes. The comparison between the systems showed identical behavior down to the system calls evoking GraphicsMagick, so the problem could only be in this library. Some more testing revealed that GM was silently dying with each of the icon creation calls on the remote machine and left a zero byte target image file. My local version behaved nicely. Updating GM on the remote machine solved the problem.
The affected version of GM is 1.2.2. Older AND newer versions work nicely (I positively tested 1.1.7, 1.3.7 and 1.3.12). This is the call that crashed GM:
C:Program FilesGraphicsMagick-1.2.2-Q8gm.exe convert +profile '*' -geometry 22x22! -colors 64 "typo3conf/ext/file_explorer/icons/mimetypes/medium/audio-x-generic.png" "typo3temp/pics/5c9e57d0ab.png"
Interesting side observation:
The PNG icons created with the 1.1 series of GM were 8 bit deep and less than half the size of the icons created with the 1.3 series of GM, which were 32 bit deep. The calls for both versions were identical though (see above).