Note: notes when base64 encoding is used as querystring

The plus sign (+) is part of base64 encoding, And the plus sign is treated as a space in querystring.
Therefore, when a string containing base64 encoding is directly used as a part of the URL, if it contains a plus sign, then when querystring is used for reading, base64 decoding will cause an error.

There are two solutions:
First, base64 strings are used as part of the URL and encoded using functions such as urlencode;
Second, after receiving the base64 string, replace the space in the string with the plus sign and decode it.