diff --git a/announce.py b/announce.py
index 81c5bf3d6..eec04fa13 100644
--- a/announce.py
+++ b/announce.py
@@ -88,8 +88,9 @@ def undoAnnounceCollectionEntry(recentPostsCache: {}, \
         nickname=getNicknameFromActor(actor)
         cachedPostFilename= \
             getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-        if os.path.isfile(cachedPostFilename):
-            os.remove(cachedPostFilename)
+        if cachedPostFilename:
+            if os.path.isfile(cachedPostFilename):
+                os.remove(cachedPostFilename)
         removePostFromCache(postJsonObject,recentPostsCache)
 
         if not postJsonObject.get('type'):
@@ -144,8 +145,9 @@ def updateAnnounceCollection(recentPostsCache: {}, \
         nickname=getNicknameFromActor(actor)
         cachedPostFilename= \
             getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-        if os.path.isfile(cachedPostFilename):
-            os.remove(cachedPostFilename)
+        if cachedPostFilename:
+            if os.path.isfile(cachedPostFilename):
+                os.remove(cachedPostFilename)
         removePostFromCache(postJsonObject,recentPostsCache)
 
         if not postJsonObject.get('object'):
diff --git a/bookmarks.py b/bookmarks.py
index 0c365250e..29483df8c 100644
--- a/bookmarks.py
+++ b/bookmarks.py
@@ -37,8 +37,9 @@ def undoBookmarksCollectionEntry(recentPostsCache: {}, \
     nickname=getNicknameFromActor(actor)
     cachedPostFilename= \
         getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-    if os.path.isfile(cachedPostFilename):
-        os.remove(cachedPostFilename)
+    if cachedPostFilename:
+        if os.path.isfile(cachedPostFilename):
+            os.remove(cachedPostFilename)
     removePostFromCache(postJsonObject,recentPostsCache)
 
     if not postJsonObject.get('type'):
@@ -143,8 +144,9 @@ def updateBookmarksCollection(recentPostsCache: {}, \
         nickname=getNicknameFromActor(actor)
         cachedPostFilename= \
             getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-        if os.path.isfile(cachedPostFilename):
-            os.remove(cachedPostFilename)
+        if cachedPostFilename:
+            if os.path.isfile(cachedPostFilename):
+                os.remove(cachedPostFilename)
         removePostFromCache(postJsonObject,recentPostsCache)
 
         if not postJsonObject.get('object'):
diff --git a/like.py b/like.py
index b93ae4113..e834b0eb4 100644
--- a/like.py
+++ b/like.py
@@ -35,8 +35,9 @@ def undoLikesCollectionEntry(recentPostsCache: {}, \
         nickname=getNicknameFromActor(actor)
         cachedPostFilename= \
             getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-        if os.path.isfile(cachedPostFilename):
-            os.remove(cachedPostFilename)
+        if cachedPostFilename:
+            if os.path.isfile(cachedPostFilename):
+                os.remove(cachedPostFilename)
         removePostFromCache(postJsonObject,recentPostsCache)
 
         if not postJsonObject.get('type'):
@@ -117,8 +118,9 @@ def updateLikesCollection(recentPostsCache: {}, \
         nickname=getNicknameFromActor(actor)
         cachedPostFilename= \
             getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
-        if os.path.isfile(cachedPostFilename):
-            os.remove(cachedPostFilename)
+        if cachedPostFilename:
+            if os.path.isfile(cachedPostFilename):
+                os.remove(cachedPostFilename)
         removePostFromCache(postJsonObject,recentPostsCache)
 
         if not postJsonObject.get('object'):
diff --git a/utils.py b/utils.py
index 094b82311..8be29b6fd 100644
--- a/utils.py
+++ b/utils.py
@@ -447,8 +447,15 @@ def getCachedPostFilename(baseDir: str,nickname: str,domain: str, \
                           postJsonObject: {}) -> str:
     """Returns the html cache filename for the given post
     """
+    cachedPostDir=getCachedPostDirectory(baseDir,nickname,domain)
+    if not os.path.isdir(cachedPostDir):
+        print('ERROR: invalid html cache directory '+cachedPostDir)
+        return None
+    if '@' not in cachedPostDir:
+        print('ERROR: invalid html cache directory '+cachedPostDir)
+        return None
     cachedPostFilename= \
-        getCachedPostDirectory(baseDir,nickname,domain)+ \
+        cachedPostDir+ \
         '/'+postJsonObject['id'].replace('/activity','')
     print('CACHE: 1 '+nickname+' '+domain+' '+cachedPostFilename)
     if '#' in cachedPostFilename:
diff --git a/webinterface.py b/webinterface.py
index 76bdfaf42..8f66d6f5a 100644
--- a/webinterface.py
+++ b/webinterface.py
@@ -1948,6 +1948,9 @@ def loadIndividualPostAsHtmlFromCache(baseDir: str,nickname: str,domain: str, \
     cachedPostFilename=getCachedPostFilename(baseDir,nickname,domain,postJsonObject)
 
     postHtml=''
+    if not cachedPostFilename:
+        return postHtml
+        
     if not os.path.isfile(cachedPostFilename):
         return postHtml