Hatch Creation - A Closed Boundary Could Not Be Created Issue

[a.tennant1]

Hi there, 

I am trying to create a hatch for an outline of trees I have created for my AutoCAD drawing. Autocad is saying that a closed boundary could not be determined, however I have closely inspected the shape created with lines and cannot find any gaps. Also, the places where the hatch tool has circled with a red circle are actually at line intersection points that are not even part of the shape I am trying to hatch, but lines elsewhere in my drawing's workspace. I have traced over the shape created with lines with the polyline tool, so it is one continuous polyline, and it still says that a closed boundary could not be determined. I have tried using the flaten command, the JOIN command in PEDIT, turning it into a REGION, which it does successfully (I believe this means that the shape is closed and can be hatched), exploding and joining it again, and adjusting the Gap Tolerence in HATCH. 

I have attached the file so you can see for yourself incase I'm missing anything. 

I'm using Autodesk AutoCAD 2025

Thanks so much for your help in advance. 

[Kent1Cooper]

I can't explain why it doesn't work in pick-inside-the-area mode, but for me, at least it works in select-objects mode.

[pendean]

@a.tennant1 Interesting alert came up with your file

And you are so far far far away from 0,0,0 too

The reason you may not be able to just pick inside is your treeline might just be too complex? But honestly, this is AutoCAD, so picking inside shapes should be the second thing you try, never the first: selecting outlines should be the first thing you use.

[Kent1Cooper]

You really ought to strip posted drawings down to only what's relevant to the question.  But when I got rid of extraneous Layout tabs, and the mega-Hatch elsewhere, and Moved the outline closer to the origin just in case, and Purged and LAYDEL'd the heck out of it, it still didn't work in pick-in-the-area mode.  I eventually found this situation:

at one of the shorter "tree trunks" near the middle.  The problem seems to be the self-intersection of the Polyline.  Pulling that point that touches the leftward edge away from it allowed HATCH to work as expected [for me].