diff --git a/src/main.cpp b/src/main.cpp
index 3f79c13eb..5dc93c611 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -6890,7 +6890,15 @@ void static ProcessGetData(CNode* pfrom)
                     CBlock block;
                     if (!ReadBlockFromDisk(block, (*mi).second,1))
                     {
-                        assert(!"cannot load block from disk");
+                        // A block we advertised (BLOCK_HAVE_DATA) failed to load from disk: a transient
+                        // I/O error or on-disk corruption. This previously asserted and crashed the whole
+                        // node -- any peer getdata for such a block could take us down. Log and drop this
+                        // peer instead; it can re-fetch from another node. (The bulk GETBLOCKSTREAM serve
+                        // path already fails gracefully rather than asserting.)
+                        LogPrintf("%s: ReadBlockFromDisk failed for block %s (peer=%i);"
+                                  " disconnecting peer instead of asserting\n",
+                                  __func__, inv.hash.ToString(), pfrom->GetId());
+                        pfrom->fDisconnect = true;
                     }
                     else
                     {