NationalSecurityAgency/ghidra · error · MemoryAccessException

Guest address ${addr} is not mapped, or the mapped address d

Error message

Guest address ${addr} is not mapped, or the mapped address does not exist in host memory

What it means

getByte reads one byte via getBytes(addr, val); if zero bytes were returned it throws MemoryAccessException naming the guest address: "Guest address X is not mapped, or the mapped address does not exist in host memory". Either no guest-to-host mapping covers the address, or a mapping exists but the host side has no backing memory for the snapshot.

Source

Thrown at Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/guest/DBTraceGuestPlatformMappedMemory.java:392

		return buffer.position() - startPos;
	}

	protected ByteBuffer getBytesInFull(Address address, int len) throws MemoryAccessException {
		ByteBuffer buf = ByteBuffer.allocate(len);
		if (getBytes(buf, address) != len) {
			throw new MemoryAccessException("Could not read enough bytes");
		}
		if (!isBigEndian()) {
			buf.order(ByteOrder.LITTLE_ENDIAN);
		}
		return buf;
	}

	@Override
	public byte getByte(Address addr) throws MemoryAccessException {
		byte[] val = new byte[1];
		if (getBytes(addr, val) < 1) {
			throw new MemoryAccessException("Guest address " + addr.toString() +
				" is not mapped, or the mapped address does not exist in host memory");
		}
		return val[0];
	}

	@Override
	public int getBytes(Address addr, byte[] dest) throws MemoryAccessException {
		return getBytes(addr, dest, 0, dest.length);
	}

	@Override
	public int getBytes(Address addr, byte[] dest, int destIndex, int size)
			throws MemoryAccessException {
		return getBytes(ByteBuffer.wrap(dest, destIndex, size), addr);
	}

	@Override
	public short getShort(Address addr) throws MemoryAccessException {

View on GitHub (pinned to d5f144c24d)

Solutions

1. Confirm a mapping exists for the address and that host memory is populated for the snapshot before reading.
2. Add the missing mapping and/or write host bytes for the snapshot.
3. Catch MemoryAccessException and treat the address as unmapped.

Example fix

// before
byte b = guestMem.getByte(addr);

// after
try {
    byte b = guestMem.getByte(addr);
} catch (MemoryAccessException e) {
    // unmapped or unmapped host backing: handle gracefully
}

// confirm a mapping covers the address and host memory is populated
if (platform.mapGuestToHost(addr) == null) { /* unmapped; skip */ }

try { byte b = guestMem.getByte(addr); }
catch (MemoryAccessException e) { /* unmapped guest or missing host backing */ }

When it happens

Trigger: Reading a guest address outside any addMappedRange; reading inside a mapping whose host address has no written memory for the current snapshot.

Common situations: Emulation touching unmapped guest memory; querying before host memory has been populated for the snapshot; stale mappings after host memory was cleared.

Related errors

• Could not read enough bytes
• Register {register} is not mapped
• Space does not exist
• %s: %s
• Failed to read memory

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/3192ab6ebaba8cd1. Report an issue: GitHub.