Error code: SBOX_FATAL_MEMORY_EXCEEDED

SD777  SBOX_FATAL_MEMORY_EXCEEDED means that the tab used more memory than permitted for the sandboxed process.

Edge currently sets the same limits as Chrome; the limits are so high (4gb-16gb) that exceeding them is almost always an indication of a memory leak or JavaScript error on the part of the site:

   int64_t physical_memory = base::SysInfo::AmountOfPhysicalMemory();

    if (sandbox_type == SandboxType::kGpu && physical_memory > 64 * GB) {

      memory_limit = 64 * GB;

    } else if (sandbox_type == SandboxType::kGpu && physical_memory > 32 * GB) {

      memory_limit = 32 * GB;

    } else if (physical_memory > 16 * GB) {

      memory_limit = 16 * GB;

    } else if (physical_memory > 8 * GB) {

      memory_limit = 8 * GB;

    }

Does this problem reproduce if you run Edge InPrivate without any extensions loaded?