Thanks, that was a very interesting link! My testing confirms the behaviour, and is even worse (writes fail when there is about 40% space available). My conclusion is that SPIFFS is totally unreliable (files vanish suddenly after the file becomes a certain size; and I do not know at which stage that...

As you can see also the write (append) operations before the error occurs are failing. As you can see my github (see link above) following code is executed: fseek(f, 0, SEEK_END); fprintf(f, "this is a log test string to fill up the file, for testing whether everything works OK\n"); fclose(f); ret =...

After a couple of succesfull writes to the file I got errno 5: I (347) example: Initializing SPIFFS I (347) example: Partition size: total: 52961, used: 45933 I (357) example: Checking for existing file or creating new file I (357) example: Using existing file: /spiffs/test.txt I (407) example: Part...

Maybe stupid question, but I don't know how to get the errno; the fopen() only returns a pointer, and that is NULL. Via the gdbstub I could get following info, does that help? (gdb) bt #0 esp_crosscore_int_send_yield (core_id=0) at /home/baswi/esp/esp-idf/components/esp_system/crosscore_int.c:145 #1...

For everyone that wishes to reproduce the problem, I have added my test project to github, see https://github.com/basaandewiel/spiffsT ... ple_main.c
(look in main file for "this should not happen"

You are correct. I added a test, and it seems that after some time (after writing several strings to the file), suddenly fopen() of the existing file returns a NULL pointer. So I know why fseek() fails, but now is the question why fopen() fails after some time. I also made a simple test program, ded...

I am writing a file in SPIFFS. When the file size is about 60% or more of the available space as reported by esp_spiffs_info, then after some time the program crashes with LoadProhibited in fseek. Guru Meditation Error: Core 0 panic'ed (LoadProhibited). Exception was unhandled. Core 0 register dump:...

In my code the only thing I do is HTTP Post to telelgram.org every 10 seconds. After 6 or 7 succesful POST messages, the program crashes (easily reproducable). My code is based on the official http_post example. And wifi connection is based on the wifi connection example. I am using esp idf v4.2. Ou...