Erro
Path
bobsflowcontrol/graphics/entity/pipe-brass-elbow.png does not match any enabled mod.

I'm also using "Flow Control" this when alone works normally.

I am running into this as well.

-Kyle

I don't know if either of you will see this, but for anyone else who runs into this problem:

The fix is quite simple, only involving 2 lines.
In data-final-fixes.lua (should be in data.lua, but oh well, apparently the original had it here also):
Line 29 and 30: Change bobsflowcontrol/.. to flowcontrolforbob/..
(Can't figure out how to format this to show, but there are two _ on each side of "bobsflowcontrol" and "flowcontrolforbob")

The issue is that the name of the mod was changed without also changing these lines, causing it to look for the images in the wrong place, and as such causing this error you saw.

Yes, i have same error. Mod has name flowcontrolforbob and path to image contains mod name, not folder inside mod.

Thanks LightningDragon10065, this fixes the problem.
A small note for @all: do not remove the underscores when editing the name, only change the name.

fixed
thanks for reporting