I made this website in 2015.
I woke up to this error today:

ERROR: Tag "input": 'name' attribute (PaymentLogo) contains invalid characters. (Only lowercase[a-z], numerals[0-9], hyphen and underscore permitted.)

The site has been functioning well until now. Similar errors on various pages. Is it possible to fix this without losing my database or redoing my database.

[trendoman]

Yeah, it is possible to outswim the tide of errors without losing anything. Ask someone experienced to help you (I expect the website is online and ftp / db credentials are available).