Ayende @ Rahien

My name is Oren Eini
Founder of Hibernating Rhinos LTD and RavenDB.
You can reach me by phone or email:


+972 52-548-6969

, @ Q c

Posts: 6,026 | Comments: 44,844

filter by tags archive

Strange production errors

time to read 1 min | 135 words

The following code cause a really strange error in production:

new MailAddress("test@gmail.​com");

The specified string is not in the form required for an e-mail address.


Obviously it is!

After immediately leaping to the conclusion that .NET is crap and I should immediately start writing my own virtual machine, I decided to dig a little deeper:

Character Code
t 116
e 101
s 115
t 116
@ 64
g 103
m 109
a 97
i 105
l 108
. 46
? 8203
c 99
o 111
m 109

8203 stands for U+200B or zero width space.

I guess that someone with a software testing background decided to get medieval on one of our systems.


Phil Jones

Holy crap!

I just debugged the exact same issue on my client's system.

We were all similarly scratching our heads till I had to use to view source.

My solution:

// Remove HTML characters email = Regex.Replace(email, "&#[0-9]+;", "");

(A big hacky)


This usually happens when you copy-paste from Word. That guy isn't too sophisticated, he is just lazy...

Nic Wise

We've just been dealing with something similar.

select id, catnum from table;

1 ABCD-1234 2 ABCD-1234

select id, '[' + catnum + ']' from table; 1 [ABCD-1234] 2 [ABCD-1234

(catnum is ment to be unique, too!)

Got some unicode nonsense going on in there somewhere.... I suspect a newline, but we still can't find it.

Mikkel Christensen

Another problem to watch out for when using the MailAddress constructor:



I get this quite a lot in our databases. The source is usually legacy processes that rely on Excel spreadsheets/vba for data loading (yuck).


This is a quite valid and common character in some languages, such as Persian (it is called Zero-Width Non Jointer) and joins different parts of a single word, when you don't want it get separated when word-wrapping happens. E.g., the following word contains a ZWNJ: می‌روم

Since it is a very common character for some languages it may happen usually that somebody changes the keyboard language accidentally and enter it without purpose.

Comment preview

Comments have been closed on this topic.


No future posts left, oh my!


  1. Technical observations from my wife (3):
    13 Nov 2015 - Production issues
  2. Production postmortem (13):
    13 Nov 2015 - The case of the “it is slow on that machine (only)”
  3. Speaking (5):
    09 Nov 2015 - Community talk in Kiev, Ukraine–What does it take to be a good developer
  4. Find the bug (5):
    11 Sep 2015 - The concurrent memory buster
  5. Buffer allocation strategies (3):
    09 Sep 2015 - Bad usage patterns
View all series


Main feed Feed Stats
Comments feed   Comments Feed Stats