I have used Shotcut for several projects before I experienced this.
I edited a video, then went to export. It worked fine for a while, with normal resource values, until it reached 81%. At this point, the RAM usage slowly climbed, reaching up to 20GB (I have 24GB, and my computer never reached 100% ram). After several minutes of staying at high values, it failed.
After I realised that it had failed, I tried again. Same thing. After that, I restarted my PC and tried again. Same thing. I reinstalled Shotcut and tried again. Same thing. I did some reasearch after this, there were some posts about this;
I tried messing with export settings, to no avail
I tried running qmelt from the command line, same thing.
I tried running Shotcut as administrator. Same thing.
I tried re-editing it. Same thing.
I tried different footage. Same thing.
I tried different export presets. Same thing.
I am using an AMD Ryzen 5 (6 cores, 3.6 MHz, 12 threads) and 24 GB of DDR4 RAM. I have a 1000GB SSD which has 600GB free. I have a GT710, which has 1GB of GRAM.
I am using an up-to-date copy of Windows 10.