diff --git a/devtools/client/aboutdebugging/test/head.js b/devtools/client/aboutdebugging/test/head.js
index 109e42c3ea56..8ea562fe1d1a 100644
--- a/devtools/client/aboutdebugging/test/head.js
+++ b/devtools/client/aboutdebugging/test/head.js
@@ -433,5 +433,6 @@ function enableServiceWorkerDebugging() {
       ["dom.ipc.processCount", 1],
     ]};
     SpecialPowers.pushPrefEnv(options, done);
+    Services.ppmm.releaseCachedProcesses();
   });
 }
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 01cf04883a1a..281c608a25dd 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -746,6 +746,10 @@ ContentParent::IsMaxProcessCountReached(const nsAString& aContentProcessType)
 /*static*/ void
 ContentParent::ReleaseCachedProcesses()
 {
+  if (!GetPoolSize(NS_LITERAL_STRING(DEFAULT_REMOTE_TYPE))) {
+    return;
+  }
+
   // We might want to extend this for other process types as well in the future...
   nsTArray<ContentParent*>& contentParents = GetOrCreatePool(NS_LITERAL_STRING(DEFAULT_REMOTE_TYPE));
   ContentProcessManager* cpm = ContentProcessManager::GetSingleton();