Vernier Software and Technology
Vernier Software & Technology
Tech Info Library

Logger Pro crashes after opening a qmbl file from LabQuest.

A problem in LabQuest 1.2 can create the following crash in Logger Pro. This is often found with spectrometers, but other sensors can cause the same issue.

Connect a spectrometer to LabQuest running LabQuest App 1.2.
Calibrate, take data.
Disconnect the spectrometer.
Connect a USB flash drive to the LabQuest.
Save out the LabQuest session into a qmbl file on the flash drive.
Move the flash drive to a computer.
Open the qmbl file in Logger Pro.

At this point Logger Pro will be unstable, and will eventually crash with an assert, at varying line numbers depending on the version of Logger Pro. 3.8, line 9302. 3.7, line 9271, 3.6.1, line 9134.

This particular problem is averted by using LabQuest App 1.3 or newer. This upgrade is free, and can be found at

We also strongly recommend updating Logger Pro to version 3.8 or newer, which is also a free upgrade, available at

Note that since the problem is created by LabQuest App 1.2, any files created by that version will always create instabilities when opened in Logger Pro 3.8 and earlier. Opening a LabQuest 1.2 file and saving it in 1.3 will not fix the problem.

However, you can still recover data from LabQuest 1.2 qmbl files using the following steps, which will import from, rather than open, the qmbl file:

Make the qmbl file available on your computer, either by copying it there or by having it on an attached USB drive.
Launch Logger Pro (preferably 3.8).
-->Do not open the qmbl file, or double-click on it.
Choose Import From --> Logger Pro file... from the File menu.
Navigate to your qmbl file, and choose it.
Logger Pro will import the data from the qmbl file.

This will make the data available. Note that the data will not be plotted automatically, and that there will be multiple data sets present. You will need to graph the data by dragging the column headers to the X or Y axes of the graph; you'll need then to autoscale the graph. If you create calculated columns, you'll need to choose the data set that is not titled "Data Set."

Similar problems can arise with other sensors, usually if they are disconnected before the qmbl file is saved out.

To create files in LabQuest that do not cause instabilities, use LabQuest 1.3 or newer.

You can determine your LabQuest App version by these steps:

Tap the Home Icon
Select Control Panel
Select System Information
Read the system information summary tab for version number. If there is no obvious version, you are NOT running version 1.3.

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