diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index 195088cf1..87edc757d 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -223,7 +223,6 @@ const contentObserver = {
                 } else {
                     // Sandbox appears void.
                     // I've seen this happens, need to investigate why.
-                    
                 }
             };
         }
@@ -325,6 +324,7 @@ const contentObserver = {
             lss(this.contentBaseURI + 'vapi-client.js', sandbox);
             lss(this.contentBaseURI + 'contentscript-start.js', sandbox);
         } catch (ex) {
+            //console.exception(ex.msg, ex.stack);
             return;
         }
 
diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index f8ed63e21..dab4e4f86 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -791,7 +791,7 @@ var tabWatcher = (function() {
         }
         var tabId = browserToTabIdMap.get(browser);
         if ( tabId === undefined ) {
-            tabId = 't' + tabIdGenerator++;
+            tabId = '' + tabIdGenerator++;
             browserToTabIdMap.set(browser, tabId);
             tabIdToBrowserMap.set(tabId, browser);
         }
@@ -1212,9 +1212,13 @@ var httpObserver = {
         5: 'object',
         6: 'main_frame',
         7: 'sub_frame',
+        10: 'ping',
         11: 'xmlhttprequest',
         12: 'object',
         14: 'font',
+        15: 'media',
+        16: 'websocket',
+        19: 'beacon',
         21: 'image'
     },
 
diff --git a/platform/firefox/vapi-client.js b/platform/firefox/vapi-client.js
index b5fd7d4c8..b62a9b593 100644
--- a/platform/firefox/vapi-client.js
+++ b/platform/firefox/vapi-client.js
@@ -33,7 +33,7 @@
 
 var vAPI = self.vAPI = self.vAPI || {};
 vAPI.firefox = true;
-vAPI.sessionId = String.fromCharCode(Date.now() % 25 + 97) +
+vAPI.sessionId = String.fromCharCode(Date.now() % 26 + 97) +
     Math.random().toString(36).slice(2);
 
 /******************************************************************************/
@@ -127,7 +127,13 @@ vAPI.messaging = {
                     return;
                 }
 
-                self.injectScript(details.file);
+                // TODO: investigate why this happens, and if this happens
+                // legitimately (content scripts not injected I suspect, so
+                // that would make this legitimate).
+                // Case: open popup UI from icon in uBlock's logger
+                if ( typeof self.injectScript === 'function' )  {
+                    self.injectScript(details.file);
+                }
             }
         };
     },