Cannot dereference iterator at end of result set! ROS2

I have error: Cannot dereference iterator at end of result set!

This seems to be a error caused due to rosbag segmention.

YAML file

rosbag2_bagfile_information:

version: 4

storage_identifier: sqlite3

relative_file_paths:

- lidar_2021-08-23_11-42-50_0.db3

- lidar_2021-08-23_11-42-50_1.db3

- lidar_2021-08-23_11-42-50_2.db3

- lidar_2021-08-23_11-42-50_3.db3

- lidar_2021-08-23_11-42-50_4.db3

- lidar_2021-08-23_11-42-50_5.db3

- lidar_2021-08-23_11-42-50_6.db3

- lidar_2021-08-23_11-42-50_7.db3

- lidar_2021-08-23_11-42-50_8.db3

- lidar_2021-08-23_11-42-50_9.db3

- lidar_2021-08-23_11-42-50_10.db3

- lidar_2021-08-23_11-42-50_11.db3

- lidar_2021-08-23_11-42-50_12.db3

- lidar_2021-08-23_11-42-50_13.db3

- lidar_2021-08-23_11-42-50_14.db3

- lidar_2021-08-23_11-42-50_15.db3

- lidar_2021-08-23_11-42-50_16.db3

- lidar_2021-08-23_11-42-50_17.db3

- lidar_2021-08-23_11-42-50_18.db3

- lidar_2021-08-23_11-42-50_19.db3

- lidar_2021-08-23_11-42-50_20.db3

duration:

nanoseconds: 646857706117

[Karthik Reddy Vennapureddy]

Hi Manuel,

Please reach out to us through the MathWorks® Technical Support. We may need more information to help you out.

Thanks,

Karthik Reddy

[Blue Bird]

I had exactly the same problem. Please tell me how you could solve it eventually.

I can use the bagreader to retrieve all the messages with readMessages(bagreader).

However, if I use

subset = bagreader.select("Topic","/report_timer")

I will get

>> readMessages(subset,1)

Cannot dereference iterator at end of result set!

>> readMessages(subset,2)

Cannot increment result iterator beyond result set!

Answer 1

[Karthik Reddy Vennapureddy]

Hi Blue Bird,

Reading Multiple ROS 2 bag(.db3) files from a bag folder is supported from R2023b. If you are using older release, the workaround is to read individual bag files by providing bag file name or combine segmented bag files into one large bag file and read that bag folder.

If it is possible, can you update your MATLAB version to R2023b and try reading the bag folder containing multiple bag files. Let us know if this resolves the problem.

Thanks,

Karthik Reddy