SQL Server Operating system error 5: "5(Access is denied.)"

I used Entity framework in my application and had this problem,I seted any permission in folders and windows services and not work,
after that I start my application as administrator (right click in exe file and select "run as admin") and that works fine.

SQL Server database engine service account must have permissions to read/write in the new folder.

Check out [this][1]

> To fix, I did the following:
>
> Added the Administrators Group to the file security permissions with
> full control for the Data file (S:\) and the Log File (T:\).
>
> Attached the database and it works fine.


[![enter image description here][2]][2]

[![enter image description here][3]][3]


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I solve this problem by adding `Full control` permission for both `.mdf` and `.ldf` files for `Users` group.

If you get this error on an `.MDF` file in the `APP_DATA` folder (or where ever you put it) for a Visual Studio project, the way I did it was to simply copy permissions from the existing `DATA` folder here (I'm using SQL Express 2014 to support an older app):

C:\Program Files\Microsoft SQL Server\MSSQL12.SQLEXPRESS2014\MSSQL\DATA

*(note: your actual install path my vary - especially if your instance name is different)*

Double click on the`DATA` folder first as administrator to make sure you have access, then open the properties on the folder and mimic the same for the `APP_DATA` folder. In my case the missing user was `MSSQL$SQLEXPRESS2014` (because I named the instance `SQLEXPRESS2014` - yours may be different). That also happens to be the SQL Server service username.

For some reason, setting all the correct permissions did not help in my case. I had a file `db.bak` that I was not able to restore due to the `5(Access is denied.)` error. The file was placed in the same folder as several other backup files and all the permissions were *identical* to other files. I was able to restore all the other files except this `db.bak` file. I even tried to change the SQL Server service log on user — still the same result. I've tried copying the file with no effect.

Then I attempted to just create an identical file by executing

```
type db.bak > db2.bak
```

instead of copying the file. And voila it worked! `db2.bak` restored successfully.

I suspect that some other problems with reading the backup file may be erroniously reported as `5(Access is denied.)` by MS SQL.

In linux, I went to `/var/opt/mssql/data/` folder and opened a terminal with `sudo` then, changed my *.mdf and *.ldf file permissions as below in which you replace `yourDB` with your Database file name and `myUser` to currently logged username:

```
chmod 755 yourDB.mdf
chown myUser yourDB.mdf

chmod 755 yourDB.ldf
chown myUser yourDB.ldf
```

After that, it was reconnected without any issue.

I had this problem. Just run SQL Server as **administrator**

It means the SSMS login user does not have permission on the .mdf file. This is how it has worked for me:

I had opened the SSMS (Run as administrator) and login as an administrator user, database right-click attach, click add, select the .mdf file, click Ok. Done.

If the database you are trying to attach is compressed it may show error message.

First you have to decompress the file. For that go to properties of mdf/ldf file >> then "Advanced" >> Uncheck "Compress Contents to save disk space" >> Press "Apply".

After that give it a try.

1) Run SQL Server management studio as Administrator
2) Log in as Windows user
3) Remove log file if you have only MDF file (haven't log file)

[![enter image description here][1]][1]

With 3 items in the above checklist, you will remove almost problems related with attach database task.


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