OS Ubuntu Ubuntu 16.04.2 LTS Apache/2.4.18 Perl v5.22.1
So I have perl code that reads a mysql database, and then creates a dynamic webpage. The code's been working great for years. A week ago, my client calls and says they are getting a 500 internal server message. I take a look and everything seems fine, but when I try to load the page, I get 500 error. In the apache error log, there's this error:
[Tue May 30 22:16:13.144199 2017] [http:error] [pid 12487] [client 184.108.40.206:55628] AH02429: Response header name '<!-- warning' contains invalid characters, aborting request
Has anyone seen this, or have any idea what is causing it?