Python errors

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Top tools (local-only)

• JSON Validator
• JSON Repair
• YAML Validator
• CSV Validator
• XML to JSON
• Base64 Encode/Decode
• URL Encode/Decode
• JWT Decoder

JSON parse / deserialize errors

Most issues are not “bad JSON” but wrong content (HTML), truncation, extra characters, invalid escapes, or encoding.

• json.decoder.JSONDecodeError: Expecting ',' delimiter: line 1 column 2 (char 1)
• json.decoder.JSONDecodeError: Expecting ':' delimiter: line 1 column 10 (char 9)
• json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
• json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
• json.decoder.JSONDecodeError: Extra data: line 1 column 2 (char 1)
• json.decoder.JSONDecodeError: Invalid \escape: line 1 column 10 (char 9)
• json.decoder.JSONDecodeError: Invalid \uXXXX escape: line 1 column 10 (char 9)
• json.decoder.JSONDecodeError: Invalid control character at: line 1 column 10 (char 9)
• json.decoder.JSONDecodeError: Unterminated string starting at: line 1 column 10 (char 9)
• JSONDecodeError: Expecting ',' delimiter: line 1 column 2 (char 1)
• JSONDecodeError: Expecting ':' delimiter: line 1 column 10 (char 9)
• JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
• JSONDecodeError: Expecting value: line 1 column 1 (char 0)
• JSONDecodeError: Extra data: line 1 column 2 (char 1)
• JSONDecodeError: Invalid \escape: line 1 column 10 (char 9)
• JSONDecodeError: Invalid \uXXXX escape: line 1 column 10 (char 9)
• JSONDecodeError: Invalid control character at: line 1 column 10 (char 9)
• JSONDecodeError: Unterminated string starting at: line 1 column 10 (char 9)
• simplejson.errors.JSONDecodeError: Expecting ',' delimiter: line 1 column 2 (char 1)
• simplejson.errors.JSONDecodeError: Expecting ':' delimiter: line 1 column 10 (char 9)
• simplejson.errors.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
• simplejson.errors.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
• simplejson.errors.JSONDecodeError: Extra data: line 1 column 2 (char 1)
• simplejson.errors.JSONDecodeError: Invalid \escape: line 1 column 10 (char 9)
• simplejson.errors.JSONDecodeError: Invalid \uXXXX escape: line 1 column 10 (char 9)
• simplejson.errors.JSONDecodeError: Invalid control character at: line 1 column 10 (char 9)
• simplejson.errors.JSONDecodeError: Unterminated string starting at: line 1 column 10 (char 9)
• TypeError: the JSON object must be str, bytes or bytearray, not bool
• TypeError: the JSON object must be str, bytes or bytearray, not dict
• TypeError: the JSON object must be str, bytes or bytearray, not float
• TypeError: the JSON object must be str, bytes or bytearray, not int
• TypeError: the JSON object must be str, bytes or bytearray, not list
• TypeError: the JSON object must be str, bytes or bytearray, not NoneType

YAML parse errors

YAML is indentation-sensitive. Fix the first reported line/column, then validate again before converting.

• yaml.composer.ComposerError: found duplicate key
• yaml.constructor.ConstructorError: could not determine a constructor for the tag
• yaml.parser.ParserError: expected <block end>, but found '<block mapping start>'
• yaml.parser.ParserError: while parsing a block mapping
• yaml.reader.ReaderError: unacceptable character #x0000
• yaml.scanner.ScannerError: found character '\t' that cannot start any token
• yaml.scanner.ScannerError: mapping values are not allowed here
• yaml.scanner.ScannerError: while scanning a simple key

CSV parser errors

CSV issues are usually delimiter + quoting rules. Find the first broken row and fix it.

• _csv.Error: field larger than field limit (131072)
• _csv.Error: line contains NUL
• _csv.Error: newline inside string
• EmptyDataError: No columns to parse from file
• Error tokenizing data. C error: Expected 5 fields in line 10, saw 7
• Error: iterator should return strings, not bytes (did you open the file in text mode?)
• ParserError: Error tokenizing data. C error: Buffer overflow caught - possible malformed input file.
• ParserError: Error tokenizing data. C error: Calling read(nbytes) on source failed. Try engine='python'.
• ParserError: Error tokenizing data. C error: EOF inside string starting at row 5
• ParserError: Error tokenizing data. C error: Expected 1 fields in line 2, saw 2
• ParserError: Error tokenizing data. C error: Expected 3 fields in line 10, saw 5

XML parsing errors

XML is strict: a single invalid character or unescaped ampersand can break parsing. Fix the first error and re-validate.

• xml.etree.ElementTree.ParseError: EntityRef: expecting ';'
• xml.etree.ElementTree.ParseError: mismatched tag: line 1, column 2
• xml.etree.ElementTree.ParseError: no element found: line 1, column 0
• xml.etree.ElementTree.ParseError: not well-formed (invalid token): line 1, column 0
• xml.etree.ElementTree.ParseError: unclosed token: line 1, column 0
• xml.etree.ElementTree.ParseError: undefined entity: line 1, column 10
• xml.parsers.expat.ExpatError: undefined entity: line 1, column 10

Encoding / token errors (Base64, URL, JWT)

Encoded strings may contain secrets. Decode locally and normalize Base64URL/percent-encoding safely.

• binascii.Error: Incorrect padding
• binascii.Error: Incorrect padding (urlsafe base64 decode)
• binascii.Error: Invalid base64-encoded string: number of data characters cannot be 1 more than a multiple of 4
• binascii.Error: Non-base64 digit found
• jwt.exceptions.DecodeError: Not enough segments
• jwt.exceptions.ExpiredSignatureError: Signature has expired
• jwt.exceptions.InvalidAudienceError: Invalid audience
• jwt.exceptions.InvalidIssuerError: Invalid issuer
• jwt.exceptions.InvalidSignatureError: Signature verification failed
• UnicodeDecodeError: 'charmap' codec can't decode byte
• UnicodeDecodeError: 'utf-8' codec can't decode byte
• UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe2 in position 10: invalid continuation byte
• UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte
• UnicodeDecodeError: 'utf-8' codec can't decode bytes in position 0-1: unexpected end of data
• UnicodeEncodeError: 'ascii' codec can't encode character
• ValueError: invalid % escape

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