I am getting the following error when attempting to upload small images (between 10K and 30K). This happens with several images therefore I don't think it's specific to a particular image file. Since my images are so small and are well within the MaxAllowedContentLength, I believe this message is simply misleading and the actual problem is probably not related to the image size at all. I get this error when I click the "browse" button on the IMG tag editor and then click "Upload".
Please note that I have implemented custom file storage which might becausing this problem. However the upload feature in the "Image Gallery" and the upload on the "Insert Image" work just fine.
cm_htmlcontent.Setting["Template-CuteEditorFileStorageType"] = typeof(MyCustomTemplateFileStorage).AssemblyQualifiedName;
cm_htmlcontent.Setting["InsertGallery-CuteEditorFileStorageType"] = typeof(MyCustomImageFileStorage).AssemblyQualifiedName;
cm_htmlcontent.Setting["InsertImage-CuteEditorFileStorageType"] = typeof(MyCustomImageFileStorage).AssemblyQualifiedName;
cm_htmlcontent.Setting["SelectImage-CuteEditorFileStorageType"] = typeof(MyCustomImageFileStorage).AssemblyQualifiedName;