There are a few software situations where the thermometer may not work. The most likely is that the php software has components missing or out of date. Unfortunately it is common with new installations of php8 that the GD Library (for graphics) software does not support the "imagecreatefromgif". The required functionality was removed from the GD library in Version 1.6. It was restored in Version 2.0.28.

Just FYI, the machine that this software is running is:

The operating system may be blank for Windows operating systems.