diff --git a/developer/src/tike/main/KeymanDeveloperOptions.pas b/developer/src/tike/main/KeymanDeveloperOptions.pas
index 3e31f27688..a2c1b2af03 100644
--- a/developer/src/tike/main/KeymanDeveloperOptions.pas
+++ b/developer/src/tike/main/KeymanDeveloperOptions.pas
@@ -82,6 +82,7 @@ type
     procedure optWriteBool(const nm: string; value: Boolean);
     procedure optWriteInt(const nm: string; value: Integer);
     procedure WriteServerConfigurationJson;
+    class function Get_Initial_DefaultProjectPath: string; static;
   public
     procedure Read;
     procedure Write;
@@ -365,7 +366,12 @@ begin
 
     FFix183_LadderLength := optReadInt(SRegValue_IDEOpt_WebLadderLength, CRegValue_IDEOpt_WebLadderLength_Default);
 
-    FDefaultProjectPath := IncludeTrailingPathDelimiter(optReadString(SRegValue_IDEOpt_DefaultProjectPath, GetFolderPath(CSIDL_PERSONAL) + CDefaultProjectPath));
+    FDefaultProjectPath := IncludeTrailingPathDelimiter(optReadString(SRegValue_IDEOpt_DefaultProjectPath, Get_Initial_DefaultProjectPath));
+    if (FDefaultProjectPath = '\') or IsRelativePath(FDefaultProjectPath) then
+    begin
+      // #11554
+      FDefaultProjectPath := Get_Initial_DefaultProjectPath;
+    end;
 
     // for consistency with Keyman.System.KeymanSentryClient, we need to use
     // reg.ReadInteger, as regReadInt, which in the dim dark past started
@@ -613,6 +619,11 @@ begin
   Result := DefaultEditorThemeItemIndex(s) >= 0;
 end;
 
+class function TKeymanDeveloperOptions.Get_Initial_DefaultProjectPath: string;
+begin
+  Result := GetFolderPath(CSIDL_PERSONAL) + CDefaultProjectPath;
+end;
+
 function LoadKeymanDeveloperSentryFlags: TKeymanSentryClientFlags;
 begin
   Result := [kscfCaptureExceptions, kscfShowUI, kscfTerminate];
diff --git a/developer/src/tike/main/UfrmMain.pas b/developer/src/tike/main/UfrmMain.pas
index b6468ba222..44b5873245 100644
--- a/developer/src/tike/main/UfrmMain.pas
+++ b/developer/src/tike/main/UfrmMain.pas
@@ -552,11 +552,22 @@ begin
 
   FFilesToOpen := TStringList.Create;
 
-  if not ForceDirectories(FKeymanDeveloperOptions.DefaultProjectPath) then
-  begin
-    // Fall back to Documents folder if we cannot create the default project path
-    // Documents folder should always exist
-    FKeymanDeveloperOptions.DefaultProjectPath := GetFolderPath(CSIDL_PERSONAL);
+  try
+    if not ForceDirectories(FKeymanDeveloperOptions.DefaultProjectPath) then
+    begin
+      // Fall back to Documents folder if we cannot create the default project path
+      // Documents folder should always exist
+      FKeymanDeveloperOptions.DefaultProjectPath := GetFolderPath(CSIDL_PERSONAL);
+    end;
+  except
+    on E:EInOutError do
+    begin
+      // If the DefaultProjectPath is a relative, invalid path, then it may
+      // cause EInOutError (#11554). Note that this exception should no longer
+      // be possible because the path is sanitized when loaded in
+      // KeymanDeveloperOptions.pas, but keeping this fallback just in case.
+      FKeymanDeveloperOptions.DefaultProjectPath := GetFolderPath(CSIDL_PERSONAL);
+    end;
   end;
 
   FFirstShow := True;