diff --git a/cf/src/connection.js b/cf/src/connection.js
index 8e79170aeb13efe8c3c77ccede0cd3a115b5e1b5..c17a54b62fefa1f13bc38cd82e25d52ed467c94e 100644
--- a/cf/src/connection.js
+++ b/cf/src/connection.js
@@ -159,6 +159,14 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     if (terminated)
       return queryError(q, Errors.connection('CONNECTION_DESTROYED', options))
 
+    // The connection lost its socket (backend death, network close) and has
+    // not reconnected yet. Reserved connections keep routing queries here,
+    // and buffering their frames would schedule a flush with nowhere to
+    // write. Refuse up front the same way `terminated` does, so the query
+    // settles immediately instead of dangling until pool shutdown.
+    if (socket === null)
+      return queryError(q, Errors.connection('CONNECTION_CLOSED', options, socket))
+
     if (stream)
       return queryError(q, Errors.generic('COPY_IN_PROGRESS', 'You cannot execute queries during copy'))
 
@@ -254,6 +262,16 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
   }
 
   function nextWrite(fn) {
+    if (socket === null) {
+      // The connection closed between this write being scheduled and the
+      // immediate firing (or a caller raced the close handler). The close
+      // path has already settled every in-flight query, so the buffered
+      // bytes have nowhere to go: drop them instead of crashing the
+      // process from a timer callback with no try/catch above it.
+      nextWriteTimer !== null && clearImmediate(nextWriteTimer)
+      chunk = nextWriteTimer = null
+      return false
+    }
     const x = socket.write(chunk, fn)
     nextWriteTimer !== null && clearImmediate(nextWriteTimer)
     chunk = nextWriteTimer = null
@@ -427,6 +445,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
       error(Errors.connection('CONNECTION_DESTROYED', options))
 
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     if (socket) {
       socket.removeListener('data', data)
       socket.removeListener('connect', connected)
@@ -440,6 +459,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     remaining = 0
     incomings = null
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     socket.removeListener('data', data)
     socket.removeListener('connect', connected)
     idleTimer.cancel()
diff --git a/cjs/src/connection.js b/cjs/src/connection.js
index 07f6716702ac888215c86ad6e0071aaf55ae519c..949aa427e1afd0f68bc4cdcdf062e571568fd24d 100644
--- a/cjs/src/connection.js
+++ b/cjs/src/connection.js
@@ -157,6 +157,14 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     if (terminated)
       return queryError(q, Errors.connection('CONNECTION_DESTROYED', options))
 
+    // The connection lost its socket (backend death, network close) and has
+    // not reconnected yet. Reserved connections keep routing queries here,
+    // and buffering their frames would schedule a flush with nowhere to
+    // write. Refuse up front the same way `terminated` does, so the query
+    // settles immediately instead of dangling until pool shutdown.
+    if (socket === null)
+      return queryError(q, Errors.connection('CONNECTION_CLOSED', options, socket))
+
     if (stream)
       return queryError(q, Errors.generic('COPY_IN_PROGRESS', 'You cannot execute queries during copy'))
 
@@ -252,6 +260,16 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
   }
 
   function nextWrite(fn) {
+    if (socket === null) {
+      // The connection closed between this write being scheduled and the
+      // immediate firing (or a caller raced the close handler). The close
+      // path has already settled every in-flight query, so the buffered
+      // bytes have nowhere to go: drop them instead of crashing the
+      // process from a timer callback with no try/catch above it.
+      nextWriteTimer !== null && clearImmediate(nextWriteTimer)
+      chunk = nextWriteTimer = null
+      return false
+    }
     const x = socket.write(chunk, fn)
     nextWriteTimer !== null && clearImmediate(nextWriteTimer)
     chunk = nextWriteTimer = null
@@ -425,6 +443,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
       error(Errors.connection('CONNECTION_DESTROYED', options))
 
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     if (socket) {
       socket.removeListener('data', data)
       socket.removeListener('connect', connected)
@@ -438,6 +457,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     remaining = 0
     incomings = null
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     socket.removeListener('data', data)
     socket.removeListener('connect', connected)
     idleTimer.cancel()
diff --git a/src/connection.js b/src/connection.js
index 1b1cccde43b4570d5d071d6ffaab2669b3c2065a..8bb205e5b4b92282711ec8d105960508ccfc4252 100644
--- a/src/connection.js
+++ b/src/connection.js
@@ -157,6 +157,14 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     if (terminated)
       return queryError(q, Errors.connection('CONNECTION_DESTROYED', options))
 
+    // The connection lost its socket (backend death, network close) and has
+    // not reconnected yet. Reserved connections keep routing queries here,
+    // and buffering their frames would schedule a flush with nowhere to
+    // write. Refuse up front the same way `terminated` does, so the query
+    // settles immediately instead of dangling until pool shutdown.
+    if (socket === null)
+      return queryError(q, Errors.connection('CONNECTION_CLOSED', options, socket))
+
     if (stream)
       return queryError(q, Errors.generic('COPY_IN_PROGRESS', 'You cannot execute queries during copy'))
 
@@ -252,6 +260,16 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
   }
 
   function nextWrite(fn) {
+    if (socket === null) {
+      // The connection closed between this write being scheduled and the
+      // immediate firing (or a caller raced the close handler). The close
+      // path has already settled every in-flight query, so the buffered
+      // bytes have nowhere to go: drop them instead of crashing the
+      // process from a timer callback with no try/catch above it.
+      nextWriteTimer !== null && clearImmediate(nextWriteTimer)
+      chunk = nextWriteTimer = null
+      return false
+    }
     const x = socket.write(chunk, fn)
     nextWriteTimer !== null && clearImmediate(nextWriteTimer)
     chunk = nextWriteTimer = null
@@ -425,6 +443,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
       error(Errors.connection('CONNECTION_DESTROYED', options))
 
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     if (socket) {
       socket.removeListener('data', data)
       socket.removeListener('connect', connected)
@@ -438,6 +457,7 @@ function Connection(options, queues = {}, { onopen = noop, onend = noop, onclose
     remaining = 0
     incomings = null
     clearImmediate(nextWriteTimer)
+    chunk = nextWriteTimer = null
     socket.removeListener('data', data)
     socket.removeListener('connect', connected)
     idleTimer.cancel()