Lightroom 5.4 assertion failed

Question

I installed Lightroom 5.4, but it will not start.  I just get a pop-up window that says "assertion failed."  I am running Windows 7 and have had no problems with Lightroom 5.3

Answer 1

Based on more customer feedbacks, we have updated the description of the problem and describe a full workaround.
This Lightroom 5.4 error condition could happen if the standard Windows "My Pictures" virtual folder for your login account points to a physical directory that no longer exists. This could happen if,
1) The directory "C:\Users\<your Windows login account name>\Pictures\" was deleted, such that your Windows "My Pictures" virtual folder points to a default directory that is missing.
2) The directory "C:\Users\<your Windows login account name>\Pictures\" still exists in your account, but your Windows registry has been mis-configured such that your "My Pictures" virtual folder actually to point to a non-default directory location that is missing.
We'll fix the bug in the next Lightroom update. In the meantime, you have a workaroud described as follows:
1) Open up Windows Explorer
2) Confirm whether the directory "C:\Users\<your Windows login account name>\Pictures\" exists. Normally Windows also shows the "Pictures" directory as the virtual folder "C:\Users\<your Windows login account name>\My Pictures\".
3) In the Windows Explorer, navigate to your account folder "C:\Users\<your Windows login account name>\" and try to create a sub-directory named "Pictures". Skip this step if Windows reports that a directory named "Pictures" already exists in your account folder.
4) Then click the Windows Start button
5) In the "Search program and files" field, type regedit and hit Enter.
6) Navigate in the registry editor to the following Windows registry key entry [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders].
7) Check the data value for the entry named "My Pictures" if there is such an entry. The Windows default should be "%USERPROFILE%\Pictures" (without the double quote). This is the same default folder as "C:\Users\<your Windows login account name>\Pictures\" that you created at step 3.
8) If it points to a non-default directory location, you need to make sure that directory exists physically. Or you can double click on the "My Pictures" entry and reset the value to"%USERPROFILE%\Pictures" (without the double quote).
9) Quit the registry editor.
10) Then log off of your account and sign back in and relaunch Lr 5.4.