Sometimes, issues with DLL files (which are related but different from PNG files) can be resolved by re-registering them. This is more relevant for DLL issues but might be worth mentioning:
Some modern systems fail to redirect Program Files (x86) correctly for older software.
touch piece_for_qpst_server.png
or
echo "" > piece_for_qpst_server.png
If reinstallation is not possible, you can manually place the missing file.
If the file is indeed part of the QPST tool suite: qpst server.png file is missing
This is the most effective solution.
Since the program is simply looking for a file with that name, you can create a fake one. Sometimes, issues with DLL files (which are related
Now, relaunch QPST. The error should disappear because the software now "sees" the file it expects.
Sometimes, Windows Defender (or other antivirus) quarantines .png files it mistakenly flags inside developer tools. or
echo "" > piece_for_qpst_server