# Error calculating Hash

**URL:** <https://forum.servoy.com/t/error-calculating-hash/20668>\
**Category:** Feedback\
**Created:** [January 21, 2022, 7:19am UTC](https://forum.servoy.com/t/error-calculating-hash/20668 "2022-01-21T07:19:35Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![briese-it](https://avatars.discourse-cdn.com/v4/letter/b/a698b9/32.png) [@briese-it](https://forum.servoy.com/u/briese-it)\
**Post date:** [January 21, 2022, 7:19am UTC](https://forum.servoy.com/t/error-calculating-hash/20668/1 "2022-01-21T07:19:35Z")

</div>

I have problem with hash calculation in Servoy 2020.3.3.3565\_LTS.  
I’m using the calculateHash function in svyIO and getting an error when trying to append:

```auto
var hex = new java.lang.StringBuilder(2 * digestBytes.length);
for (var i = 0; i < digestBytes.length; i++) {
	hex.append(HEXES.charAt((digestBytes[i] & 0xF0) >> 4)).append(HEXES.charAt((digestBytes[i] & 0x0F)));
}

```

ERROR com.servoy.j2db.util.Debug - ERROR Error calculating Hash for file “C:\Users\Michael\Documents\test.png”: Cannot find function append in object .