protobuf error for custom messages transport tutorial

edit

I also faced this issue recently. In my case, I was trying to load an SDF generated for Ignition Gazebo in Gazebo Classic. The SDF contained some plugins, and as the plugins were built for Ignition Gazebo, they pulled in different versions of ign-msgs and sdformat than Gazebo Classic uses. This mismatch then lead to the mentioned error and a segfault. To fix it, it's enough to remove the incompatible plugins from the SDF. I assume the same would happen if you'd load a Gazebo Classic SDF in Ignition Gazebo.

I faced the same problem and finally was able to get it run. Here's how I fixed it:

In the CMakeLists.txt under msgs folder, CHANGE the following code

set (msgs
  collision_map_request.proto
  ${PROTOBUF_IMPORT_DIRS}/vector2d.proto
  ${PROTOBUF_IMPORT_DIRS}/header.proto
  ${PROTOBUF_IMPORT_DIRS}/time.proto
)

to

set (msgs
  collision_map_request.proto
)

Then remake again using cmake ../ and make

Open the map_creator.world file. Under the plugin_filename tag, make sure you specify the absolute path to the library so gazebo knows how to find it, unless the lib is at the same directory with the world. For example, in my case:

<plugin filename="/home/mon/GAZEBO Tutorial/collision_map_creator_plugin/build/libcollision_map_creator.so" name="collision_map_creator"/>

Run the gazebo in --verbose mode, just to make sure no error occurs. Note: Initially, when I ran in verbose mode , it gave me error because the filename specified is just libcollision_map_creator.so but my lib is not at the same dir as my world file, which is as instructed in the tutorial.

Lastly, don't forget to export the environment variable as suggested in the tutorial

export GAZEBO_PLUGIN_PATH=$GAZEBO_PLUGIN_PATH:collision_map_creator_plugin/build

That works for me