Pausing a process brings up a "Debugger Error" dialog that says:

 "Command 'data-disassemble'. Command Args. Validation failed. Mandatory args not found: s, e. Not all arguments or options were recognised: --
"

Reproduce with:
1. Start "/sbin/ping netbeans.org" (other debugees gives similar results)
2. Add the following to end of netbeans.conf (based on "http://wiki.netbeans.org/NewAndNoteworthyNB81"):
### BEGIN
   netbeans_default_options="$netbeans_default_options -J-Dcnd.debugger.lldb=true"
   LLDB_DEBUGSERVER_PATH='/Applications/Xcode_6_3_1.app/Contents/SharedFrameworks/LLDB.framework/Versions/A/Resources/debugserver'
   export LLDB_DEBUGSERVER_PATH
### END
(note the non-standard Xcode.app location)
3. Start NetBeans
4. Change the GDB debugger path to point at lldb-mi
5. Menu: "Debug->Attach Debugger..."
6. Select the ping process (the "Executable" field is incorrect ("/sbin/ping netbeans.org"), as it includes the command arguments, I do not know whether this is significant)
7. Select OK in the Attach dialog. Attach seems to go well (i.e. Bug 251586 has been fixed).
8. Press Pause button
9. This brings up a "Debugger Error" dialog that says: "Command 'data-disassemble'. Command Args. Validation failed. Mandatory args not found: s, e. Not all arguments or options were recognised: --
"
The "Disassembly" window is topmost.

NetBeans also shows a stacktrace for the ping process that looks reasonable.

10. Menu: Window->Debugging->Debugger Console. The Debugger Console shows:
### BEGIN
This log is saved to: /var/folders/yt/g4309t6d6m50dn_g25g551rc0000gn/T/gdb-cmds8441378968416385876.log
NB build: 201505020001
(gdb)
-file-exec-and-symbols "/Users/perm/.gdbinit"
(gdb)
(gdb)
error: 'settings set' takes more arguments
error: 'settings set' takes more arguments
(gdb)
Process 14261 stopped
    frame #0: 0x00007fff8d05a3fa libsystem_kernel.dylib`__select + 10
libsystem_kernel.dylib`__select:
->  0x7fff8d05a3fa <+10>: jae    0x7fff8d05a404            ; <+20>
    0x7fff8d05a3fc <+12>: movq   %rax, %rdi
    0x7fff8d05a3ff <+15>: jmp    0x7fff8d055c78            ; cerror
    0x7fff8d05a404 <+20>: retq   

(gdb)
Process 14261 stopped
    frame #0: 0x00007fff8d05a3fa libsystem_kernel.dylib`__select + 10
libsystem_kernel.dylib`__select:
->  0x7fff8d05a3fa <+10>: jae    0x7fff8d05a404            ; <+20>
    0x7fff8d05a3fc <+12>: movq   %rax, %rdi
    0x7fff8d05a3ff <+15>: jmp    0x7fff8d055c78            ; cerror
    0x7fff8d05a404 <+20>: retq   

(gdb)
(gdb)
(gdb)
(gdb)
(gdb)
MI: Error: Command Args. Validation failed. Mandatory args not found: s, e. Not all arguments or options were recognised: --
(gdb)
### END
(I do not know what happens when lldb-mi tries to load a .gdbinit file, but I removed my .gdbinit file, so the "error: 'settings set' takes more arguments" is not related to the contents of my (nonexisting) .gdbinit file.)

NetBeans ID Dev 201505020001

llvm, lldb from git, April 21 2015 (git log in in llvm/tools/lldb shows latest commit 0cdf53f1cd80adc95a6b098af2ff55ac9de07e3c)

OS X 10.10.3, Xcode 6.3.1.