If you mean it is to large to attach in the forums, that may be the case as there is a 512kb limit, not only that you can’t attach .rar or .zip files only text based files. .txt and .log.

Give the .rar file you are uploading a unique name (e.g. forumusername-logs-folder.rar, etc), so they can identify it. It might not be a bad idea to create a text file (readme.txt) with any relevant information, avast topic URL, user name, etc. etc. in the zip file. Not to mention posting the name of the file you uploaded in the topic, this acts as another searchable reference.

Upload the .rar file to the ftp server ftp://ftp.avast.com/incoming:

  • Using Windows Explorer, Connect to the link and drag the file into the Right pane and drop it, that starts the upload, you don’t have read access to this folder.