Glad to hear that where able to resolve your issue and thank you for sharing the reason, we will add it to our knowledge base.
As for the new issue - looks like you have reserved symbols in the file name. Please check this table of reserved by web symbols and make sure you don’t have them in the file name. Also please share the file name (or full path) with which you have this issue.
We have checked the certificate file and found out that it created by the AVG antivirus. According on it’s content it’s an HTML file - please try to set .html extension for such files or contact AVG support to found out which extension should be set for such files.