Line def does not have a front side

[chaos7040]

Hello!

Could anyone help me with this problem in trying to load map into zdoom/gzdoom?

"Line def does not have a front side."

I have tried everything from deleting the lines to looking into the properties, and I cannot figure out how to fix this problem. I keep encountering the same issue with different lines, and I've tried to understand this, but I've had no luck.

Here is the WAD with the issues:

https://www.dropbox.com/sh/si020lhqh0q1lo6/AAAIK12ieohaI82AxWZ-psUWa?dl=0

Please load everything from into SLADE3 or Doom Builder 2.

[Kappes Buur]

map01 - entryway

Removing 0-length line 591
Line 842 has no front sector
Map had 2 invalid side references
Linedef 841 does not have a front side.
The following lines do not have a front sidedef: 841

You need to fix these lines to play this map.

To fix these errors you best load your map into GZDoom Builder.

Spoiler

Fix those errors and do a Map Analysis (F4) to fix anything else.

[chaos7040]

Kappes Buur said:

To fix these errors you best load your map into GZDoom Builder.

Spoiler

http://i.imgur.com/bflGLWz.png

Fix those errors and do a Map Analysis (F4) to fix anything else.

Oh wow! Thank you so much! I was using SLADE3, and for some reason GZDOOM BUILDER loads the map without that "Line Def error."

The second patch of errors you shown in the picture, is it nessisary to fix those? I am only using that for the assets, and have no experience in fixing those problems.