A few days ago I updated my Raspberry Pi (Rev. 3) to the new Raspbian 9 (based on Debian "Stretch"). Everything went fine but when I tested some of my own tools I recognized a strange behaviour concerning the GPIO pin access.
If I only use function "digitalWrite()" (C++ code) everything is fine. But if I use try to generate a PWM output at the same pin and use the function "pwmWrite()" instead then I always get a lot of file system errors "ext4_find_entry:1463" and finally the system crashes.
First I thought of a damaged SD card so I exchanged it but nothing changed. Also changing power supply (some people mentioned as helpful) did not have any effect.
Note: I checked the SD card and also the file system on other computers; it's fine! These errors only occur when PWM signals should be created. What can I do to make my programs run again?