diff --git a/js/xpconnect/src/XPCShellImpl.cpp b/js/xpconnect/src/XPCShellImpl.cpp
index 46fcabc79530..eb3eef36d1cd 100644
--- a/js/xpconnect/src/XPCShellImpl.cpp
+++ b/js/xpconnect/src/XPCShellImpl.cpp
@@ -1237,6 +1237,11 @@ int XRE_XPCShellMain(int argc, char** argv, char** envp,
       return 1;
     }
 
+    // Now that the profiler, directory services, and prefs have been
+    // initialized we can find the download directory, where the profiler can
+    // write profiles when user stops the profiler using POSIX signal handling.
+    profiler_lookup_async_signal_dump_directory();
+
     // xpc::ErrorReport::LogToConsoleWithStack needs this to print errors
     // to stderr.
     Preferences::SetBool("browser.dom.window.dump.enabled", true);
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 396efb78753b..d534bd9ef770 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -5620,6 +5620,18 @@ nsresult XREMain::XRE_mainRun() {
     // files can't override JS engine start-up prefs.
     mDirProvider.FinishInitializingUserPrefs();
 
+    // Now that the profiler, directory services, and prefs have been
+    // initialized we can find the download directory, where the profiler can
+    // write profiles when user stops the profiler using POSIX signal handling.
+    //
+    // It's possible to start and stop the profiler by sending POSIX signals to
+    // the profiler binary when Firefox is frozen. At the time when stop signal
+    // is handled, Firefox stops the profiler and dumps the profile to disk. But
+    // getting the download directory is not really possible at that time
+    // because main thread will be unresponsive. That's why we are getting this
+    // information right now.
+    profiler_lookup_async_signal_dump_directory();
+
     // Do a canary load of a JS based module here. This will help us detect
     // missing resources during startup and make us react appropriate, that
     // is inform the user before exiting with a crash.
diff --git a/tools/profiler/core/platform.cpp b/tools/profiler/core/platform.cpp
index 6a4c408ca932..6e91b6cd355e 100644
--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -49,6 +49,7 @@
 #include "mozilla/Maybe.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/Perfetto.h"
+#include "nsCExternalHandlerService.h"
 #include "nsCOMPtr.h"
 #include "nsDebug.h"
 #include "nsISupports.h"
@@ -7006,9 +7007,9 @@ void profiler_lookup_async_signal_dump_directory() {
 #if !defined(XP_WIN)
   LOG("profiler_lookup_async_signal_dump_directory");
 
-  MOZ_ASSERT(
-      NS_IsMainThread(),
-      "We can only get access to the directory service from the main thread");
+  MOZ_ASSERT(XRE_IsParentProcess() && NS_IsMainThread(),
+             "We can only get access to the directory service from the parent "
+             "process main thread");
 
   // Make sure the profiler is actually running~
   MOZ_RELEASE_ASSERT(CorePS::Exists());
@@ -7037,17 +7038,34 @@ void profiler_lookup_async_signal_dump_directory() {
 
     CorePS::SetAsyncSignalDumpDirectory(lock, Some(mozUploadDirFile));
   } else {
+#  if defined(GP_OS_android)
+    // Bug 1904639: GetPreferredDownloadsDirectory is not implemented for
+    // Android.
+    return;
+#  endif
+
     LOG("Defaulting to the user's Download directory for profile dumps");
     nsCOMPtr<nsIFile> tDownloadDir;
-    rv = NS_GetSpecialDirectory(NS_OS_DEFAULT_DOWNLOAD_DIR,
-                                getter_AddRefs(tDownloadDir));
+    nsresult rv;
+    nsCOMPtr<nsIExternalHelperAppService> svc =
+        do_GetService(NS_EXTERNALHELPERAPPSERVICE_CONTRACTID, &rv);
+
+    if (NS_FAILED(rv)) {
+      LOG("Failed to get nsIExternalHelperAppService for the download "
+          "directory. Profiler signal handling will not be able to save to "
+          "disk. Error: %s",
+          GetStaticErrorName(rv));
+      return;
+    }
+
+    rv = svc->GetPreferredDownloadsDirectory(getter_AddRefs(tDownloadDir));
     if (NS_FAILED(rv)) {
       LOG("Failed to find download directory. Profiler signal handling will "
           "not be able to save to disk. Error: %s",
           GetStaticErrorName(rv));
-    } else {
-      CorePS::SetAsyncSignalDumpDirectory(lock, Some(tDownloadDir));
+      return;
     }
+    CorePS::SetAsyncSignalDumpDirectory(lock, Some(tDownloadDir));
   }
 #endif
 }
diff --git a/xpcom/build/XPCOMInit.cpp b/xpcom/build/XPCOMInit.cpp
index a3253fffb67e..0374d39e1267 100644
--- a/xpcom/build/XPCOMInit.cpp
+++ b/xpcom/build/XPCOMInit.cpp
@@ -480,11 +480,6 @@ NS_InitXPCOM(nsIServiceManager** aResult, nsIFile* aBinDirectory,
   // to the directory service.
   nsDirectoryService::gService->RegisterCategoryProviders();
 
-  // Now that both the profiler and directory services have been started
-  // we can find the download directory, where the profiler can write
-  // profiles if necessary
-  profiler_lookup_async_signal_dump_directory();
-
   // Init mozilla::SharedThreadPool (which needs the service manager).
   mozilla::SharedThreadPool::InitStatics();