New zLib Librarys and Hardware Random Number Generator


Well-Known Member
Jun 8, 2016
recently I've send some pull requests to update zLib to a more recent version with fixes and improvements.
Secondly I've improved and updated the old implementation of rdrand (renamed by Intel to libdrng)

While the zLib librarys are included with ServUO you have to compile libdrng yourself.


Solution to: Unable to load DLL 'zlibwapi64': The specified module could not be found.

However most systems have installed a current version of Visual Studio redistributable package, if this is not the case your ServUO may not find zlibwapi64.dll even if its is in the correct folder.


Solution: You may download latest version (current Visual Studio redistributable package 2015 Update 3) from official source:

This still supports Windows XP/Server 2003. If you still have problem, you can use any older zLib. Just rename it to libwapiX.dll


All ServUO installations work out of the box with a software random number generator. Today computers have problems to generate unpredictable random numbers. As ServUO isn't using random numbers for security this is a "because we can" implementation.

If you would like to have your CPU generate random numbers (hardware random number generator) you can do it by compiling the library and putting it in your ServUO folder.


Compile with Visual Studio
./configure && make
You may check if your CPU supports rdrand on linux by running:
cat /proc/cpuinfo

You CPU flags must contain rdrand.

This may work with AMD CPUs starting 2015 (to be verified) and Intel starting with Ivy Bridge 2012 (verified).

Thank you.
Last edited:


Well, I just had a run in with this error and when I went to install the 2015 Update 3 or whatever Microsoft made me sign in to tell me that they didn't have the download anymore? Luckily, I just hit the 2017 Redistributable and that made all my wildest dreams come true and now don't crash after character creation! :D
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New Member
Oct 31, 2018
I am still getting this error! I have tried all of the possible solutions I can find on the forums! Any ideas or fixes would be greatly appreciated.