Apple - Spotlight crashes after two letters have been entered

The solution above did not work for me: problem still occurred when re-indexing was over. I found a solution here: https://discussions.apple.com/thread/8546951

You must uncheck the "Bookmarks & History" option in the Spotlight pane of System Preferences. It fixed instantly the problem for me.

After a number of frustrating days, I have finally found a solution to this problem. I reindexed the volume for Spotlight, and that solved it.

The procedure goes as follows:

1. From the Apple () menu, choose System Preferences.
2. Click Spotlight.
3. Click the Privacy tab.
4. Drag a folder or an entire volume (your hard drive) to the list. If prompted for confirmation, click OK.
5. Remove the item or volume you just added to the list by clicking it and then clicking the minus ("-") button.
6. Close Spotlight preferences.

Spotlight will re-index the contents of the folder or volume.

Source: https://support.apple.com/en-us/HT201716