Invalid length for a Base-64 char array during decoding/decryption

Question

Q: I face the following big problem :

from time to another i find the following exception:

Invalid length for a Base-64 char array

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Answer 1

string imag = img;
imag = imag.Replace("\", "");
int c = imag.Length % 4;
if ((c) != 0)
    imag = imag.PadRight((imag.Length + (4 - c)), "=");
[] converted = Convert.FromBase64String(imag);
using (System.IO.MemoryStream vstream = new System.IO.MemoryStream(converted)) {
    return Image.FromStream(vstream);
}