A seam became visible after adding a bump map

Have you flipped any ploys?

 

Well, bump maps don't work well on mirrored or flipped polys in UVW mapping, bump map inverts itself. That's what I encountered before too:

 

I find those lines can usually be fixed with smooth modifier on that face.
also make sure you don't have duplicate lines,faces.vertex.
and sometime is necessary to add/cut more lines so each vertex has 3 points of contact.
I have no issue using mirrow or flipped faces.
In your example Paul looks like your faces are not the same even if flipped/mirrored

 

That example Paul posted may be occasioned by the normal mapping plugin. To fix it, simply invert the image before using the plugin.

About those black or shadowed walls, Select all vertices and hit the Weld Window buttom under Edit poly. If it still looks like it's broken, a Welder modifier could fix it. Under Editable Poly, select all faces and add a Welder modifier. Then collapse it. If it doesn't work, you will have to proceed manually. As Nicko said, it may be caused by a 'breach' at the vertex level. As a GPS must have at least 3 points to coordinate your exact position, each face must have 3 points to calculate the incidence of the ray samples.

 

Good points bobqwerty. If it's a google mod conversion,which seems many noobs use. half the issues are caused by many duplicate vertices, faces, lines etc. == not good. then again just bad modelling can cause an issue with any user/program

Edit: for all you math lovers
https://www.mathsisfun.com/geometry/vertices-faces-edges.html

 

I know what is wrong in my example, I already fixed it in previous year . Before that I used same part of texture, but I needed to keep symetry so I inverted poly in UVW Editor window, so together with this bump map inverts too.
I don't know any advanced plug-ins for this, but I redo texture or adjust the symetry so that both polys are same.

 

Yay, I'm very proud of myself. I'm somewhat as smart as a 6 years old. No PS required.

 

cool, good to see you made some progress.
As cool paulChris suggests use the 3dmax Edit UVW's window editor to mirrow or rotate textures, well that's what I do to get them to fit in my maps

 

Well, it's quite opposite, mirroring or rotating textures in UVW window causes this bump map problems. And I can't see where PaulJChris suggested it.

 

Really? odd I use this all time, well mirrored.

 

that element will get overlapped in uvw if You clone it, make sure You re map it before rendering lightmap...

 

UV Lightmaps don't overlap. Each face is unique. If you created something or had to flatten some faces, you have to render it again. Finish LODs first, then do lightmaps.

 

I mean remap the clone...they will overlap the original faces in uvwindow and can be total black if You render it because they got rendered twice in same place...
(although that overlapped faces may help to save 2ndchannel texture space if lightmap already rendered and they have identical occlusion effect )

an inverted face can result in black texture too, it can be fixed by mirroring it..
You can select all inverted/overlapped faces in select menu