diff --git a/js/xpconnect/loader/ScriptPreloader.cpp b/js/xpconnect/loader/ScriptPreloader.cpp
index 211d2e68381b..8e6d0c65c9bb 100644
--- a/js/xpconnect/loader/ScriptPreloader.cpp
+++ b/js/xpconnect/loader/ScriptPreloader.cpp
@@ -26,7 +26,6 @@
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/ContentParent.h"
 #include "mozilla/dom/Document.h"
-#include "mozilla/scache/StartupCache.h"
 
 #include "js/CompileOptions.h"  // JS::ReadOnlyCompileOptions
 #include "js/experimental/JSStencil.h"
@@ -66,9 +65,6 @@ using mozilla::dom::AutoJSAPI;
 using mozilla::dom::ContentChild;
 using mozilla::dom::ContentParent;
 using namespace mozilla::loader;
-using mozilla::scache::StartupCache;
-
-using namespace JS;
 
 ProcessType ScriptPreloader::sProcessType;
 
@@ -396,10 +392,6 @@ Result<nsCOMPtr<nsIFile>, nsresult> ScriptPreloader::GetCacheFile(
 static const uint8_t MAGIC[] = "mozXDRcachev002";
 
 Result<Ok, nsresult> ScriptPreloader::OpenCache() {
-  if (StartupCache::GetIgnoreDiskCache()) {
-    return Err(NS_ERROR_ABORT);
-  }
-
   MOZ_TRY(NS_GetSpecialDirectory("ProfLDS", getter_AddRefs(mProfD)));
 
   nsCOMPtr<nsIFile> cacheFile;
diff --git a/js/xpconnect/loader/URLPreloader.cpp b/js/xpconnect/loader/URLPreloader.cpp
index 60a1cea3a03d..d7b3fde867be 100644
--- a/js/xpconnect/loader/URLPreloader.cpp
+++ b/js/xpconnect/loader/URLPreloader.cpp
@@ -17,7 +17,6 @@
 #include "mozilla/Services.h"
 #include "mozilla/Unused.h"
 #include "mozilla/Vector.h"
-#include "mozilla/scache/StartupCache.h"
 
 #include "MainThreadUtils.h"
 #include "nsPrintfCString.h"
@@ -45,7 +44,6 @@ bool StartsWith(const T& haystack, const T& needle) {
 }  // anonymous namespace
 
 using namespace mozilla::loader;
-using mozilla::scache::StartupCache;
 
 nsresult URLPreloader::CollectReports(nsIHandleReportCallback* aHandleReport,
                                       nsISupports* aData, bool aAnonymize) {
@@ -170,10 +168,6 @@ Result<nsCOMPtr<nsIFile>, nsresult> URLPreloader::GetCacheFile(
 static const uint8_t URL_MAGIC[] = "mozURLcachev002";
 
 Result<nsCOMPtr<nsIFile>, nsresult> URLPreloader::FindCacheFile() {
-  if (StartupCache::GetIgnoreDiskCache()) {
-    return Err(NS_ERROR_ABORT);
-  }
-
   nsCOMPtr<nsIFile> cacheFile;
   MOZ_TRY_VAR(cacheFile, GetCacheFile(u".bin"_ns));
 
diff --git a/startupcache/StartupCache.cpp b/startupcache/StartupCache.cpp
index 974e57433bf2..50ce9d8e4b2c 100644
--- a/startupcache/StartupCache.cpp
+++ b/startupcache/StartupCache.cpp
@@ -695,10 +695,6 @@ void StartupCache::IgnoreDiskCache() {
   if (gStartupCache) gStartupCache->InvalidateCache();
 }
 
-bool StartupCache::GetIgnoreDiskCache() {
-  return gIgnoreDiskCache;
-}
-
 void StartupCache::WaitOnPrefetchThread() {
   if (!mPrefetchThread || mPrefetchThread == PR_GetCurrentThread()) return;
 
diff --git a/startupcache/StartupCache.h b/startupcache/StartupCache.h
index fe1b98e6fbab..cb34c8932251 100644
--- a/startupcache/StartupCache.h
+++ b/startupcache/StartupCache.h
@@ -165,8 +165,6 @@ class StartupCache : public nsIMemoryReporter {
   // Signal that data should not be loaded from the cache file
   static void IgnoreDiskCache();
 
-  static bool GetIgnoreDiskCache();
-
   // In DEBUG builds, returns a stream that will attempt to check for
   // and disallow multiple writes of the same object.
   nsresult GetDebugObjectOutputStream(nsIObjectOutputStream* aStream,
diff --git a/toolkit/crashreporter/CrashAnnotations.yaml b/toolkit/crashreporter/CrashAnnotations.yaml
index 54236de5e708..a42849843bd4 100644
--- a/toolkit/crashreporter/CrashAnnotations.yaml
+++ b/toolkit/crashreporter/CrashAnnotations.yaml
@@ -553,11 +553,6 @@ LastInteractionDuration:
   type: integer
   ping: true
 
-LastStartupWasCrash:
-  description: >
-    True if the last startup was detected to have been a crash.
-  type: boolean
-
 MacMemoryPressure:
   description: >
     The current memory pressure state as provided by the macOS memory pressure
@@ -786,12 +781,6 @@ ShutdownProgress:
   type: string
   ping: true
 
-StartupCacheValid:
-  description: >
-    True if the startup cache was deemed valid and usable. Will be false if the
-    last session used a different browser version or had a startup cache.
-  type: boolean
-
 StartupCrash:
   description: >
     If set to 1 then this crash occurred during startup.
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 6e29a9c842bc..ee509dad31c9 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -3282,6 +3282,18 @@ static bool RemoveComponentRegistries(nsIFile* aProfileDir,
   aLocalProfileDir->Clone(getter_AddRefs(file));
   if (!file) return false;
 
+#if defined(XP_UNIX) || defined(XP_BEOS)
+#  define PLATFORM_FASL_SUFFIX ".mfasl"
+#elif defined(XP_WIN)
+#  define PLATFORM_FASL_SUFFIX ".mfl"
+#endif
+
+  file->AppendNative(nsLiteralCString("XUL" PLATFORM_FASL_SUFFIX));
+  file->Remove(false);
+
+  file->SetNativeLeafName(nsLiteralCString("XPC" PLATFORM_FASL_SUFFIX));
+  file->Remove(false);
+
   file->SetNativeLeafName("startupCache"_ns);
   nsresult rv = file->Remove(true);
   return NS_SUCCEEDED(rv) || rv == NS_ERROR_FILE_TARGET_DOES_NOT_EXIST ||
@@ -4742,17 +4754,11 @@ int XREMain::XRE_mainStartup(bool* aExitFlag) {
 
   bool lastStartupWasCrash = CheckLastStartupWasCrash().unwrapOr(false);
 
-  CrashReporter::AnnotateCrashReport(
-      CrashReporter::Annotation::LastStartupWasCrash, lastStartupWasCrash);
-
   if (CheckArg("purgecaches") || PR_GetEnv("MOZ_PURGE_CACHES") ||
       lastStartupWasCrash || gSafeMode) {
     cachesOK = false;
   }
 
-  CrashReporter::AnnotateCrashReport(
-      CrashReporter::Annotation::StartupCacheValid, cachesOK && versionOK);
-
   // Every time a profile is loaded by a build with a different version,
   // it updates the compatibility.ini file saying what version last wrote
   // the fastload caches.  On subsequent launches if the version matches,