Unterminated string in JSON (and bad control character in string literal)

What the errors mean

A JSON string starts and ends with a double quote, may not contain a raw line break or tab, and writes a double quote or backslash inside it as \" or \\. Break any of those rules and the parser reports one of: "Unterminated string in JSON at position N" (it reached the end of the text without finding the closing quote), "Bad control character in string literal in JSON at position N" (a raw newline or tab inside a string), or "Bad escaped character in JSON at position N" (a backslash followed by something that is not an escape). Python words them "Unterminated string starting at", "Invalid control character at" and "Invalid \escape".

The editor above opens on a string with a raw line break. Click Validate to see the line it reports.

Causes and fixes

Messages are from Node.js; Python's wording is given in brackets where it differs.

{"a": "hello}

{"a": "hello"}

{"a": "line1
line2"}

{"a": "line1\nline2"}

{"a": "say "hi" now"}

{"a": "say \"hi\" now"}

{"p": "C:\Users\ada"}

{"p": "C:\\Users\\ada"}

{"a": "hel

{"a": "hello"}