System.IO.File.ReadAllBytes Access to the path denied - asp.net

Question

Am running the project on the visual studio 2015, When I tried to read the PDF its giving me the following error;
Access to the path 'E:\FILE\FILEUPLOAD\InnerFile\File' is denied.
Function Defination
var cd = new System.Net.Mime.ContentDisposition { FileName = "PDF.pdf", Inline = true };
string contentType = MimeMapping.GetMimeMapping("PDF.pdf");
Response.AppendHeader("Content-Disposition", cd.ToString());
var innerPath = "InnerFile/File" ;
FileInfo fi = new FileInfo(PDFUploadRootPath + innerPath + "/PDF.pdf");
byte[] bytes = System.IO.File.ReadAllBytes(PDFUploadRootPath + innerPath);
return File(bytes, contentType);
NOTE:
Given Full permission to user
Physically File Exists
I dont understand what to do now please help!

Answer 1

Your FileInfo instance indeed references 'E:\FILE\FILEUPLOAD\InnerFile\File\PDF.pdf':
FileInfo fi = new FileInfo(PDFUploadRootPath + innerPath + "/PDF.pdf");
but when trying to read the file contents you forgot the file name and only use the path 'E:\FILE\FILEUPLOAD\InnerFile\File':
byte[] bytes = System.IO.File.ReadAllBytes(PDFUploadRootPath + innerPath);
Thus, also add the file name for reading all file bytes:
byte[] bytes = System.IO.File.ReadAllBytes(PDFUploadRootPath + innerPath + "/PDF.pdf");
Furthermore, as others have mentioned in comments, you should really use Path.Combine to glue path parts together, not simple string concatenation...

Answer 2

Try using FileStream instead of byte array for reading the pdf file.
FileStream templateFileStream = File.OpenRead(filePath);
return templateFileStream;
Also check (through code) if user has write permission to directory or path:
public static bool HasUserWritePermission(String path, String NtAccountName)
{
DirectoryInfo di = new DirectoryInfo(path);
DirectorySecurity acl = di.GetAccessControl(AccessControlSections.All);
AuthorizationRuleCollection rules = acl.GetAccessRules(true, true, typeof(NTAccount));
Boolean hasPermission = false;
//Go through the rules returned from the DirectorySecurity
foreach (AuthorizationRule rule in rules)
{
//If we find one that matches the identity we are looking for
if (rule.IdentityReference.Value.Equals(NtAccountName, StringComparison.CurrentCultureIgnoreCase))
{
//Cast to a FileSystemAccessRule to check for access rights
if ((((FileSystemAccessRule)rule).FileSystemRights & FileSystemRights.WriteData) > 0)
{
hasPermission = true;
}
else
{
hasPermission = false;
}
}
}
return hasPermission;
}