--- a/gfx/ipc/GPUProcessManager.cpp
+++ b/gfx/ipc/GPUProcessManager.cpp
@@ -151,16 +151,20 @@ GPUProcessManager::DisableGPUProcess(con
     return;
   }
 
   gfxConfig::SetFailed(Feature::GPU_PROCESS, FeatureStatus::Failed, aMessage);
   gfxCriticalNote << aMessage;
 
   DestroyProcess();
   ShutdownVsyncIOThread();
+
+  if (nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService()) {
+    obs->NotifyObservers(nullptr, "gpu-process:disabled", nullptr);
+  }
 }
 
 void
 GPUProcessManager::EnsureGPUReady()
 {
   if (mProcess && !mProcess->IsConnected()) {
     if (!mProcess->WaitForLaunch()) {
       // If this fails, we should have fired OnProcessLaunchComplete and

--- a/toolkit/content/aboutSupport.js
+++ b/toolkit/content/aboutSupport.js
@@ -292,16 +292,22 @@ var snapshotFormatters = {
 
       if (gpuProcessPid != -1) {
         let gpuProcessKillButton = $.new("button");
 
         gpuProcessKillButton.addEventListener("click", function() {
           windowUtils.terminateGPUProcess();
         });
 
+        let listener = function(subject, topic) {
+          gpuProcessKillButton.disabled = true;
+          Services.obs.removeObserver(listener, "gpu-process:disabled");
+        };
+        Services.obs.addObserver(listener, "gpu-process:disabled", false);
+
         gpuProcessKillButton.textContent = strings.GetStringFromName("gpuProcessKillButton");
         addRow("diagnostics", "GPUProcessPid", gpuProcessPid);
         addRow("diagnostics", "GPUProcess", [gpuProcessKillButton]);
       }
     }
 
     // graphics-failures-tbody tbody
     if ("failures" in data) {