Lightroom: LR4 has stopped opening. Error message "Assertion failed" (Win 7)

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  • Problem
  • Updated 7 years ago
  • Solved
  • (Edited)
LR4 had been working perfectly. Now it will not open and I get a message "Assertion failed". Win 7. I had installed a psd codec which I then uninstalled and I used system restore. Still no open. I uninstalled and reinstalled to no effect.
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Sarah Nordquist

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Posted 7 years ago

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Becky Sowada, Adobe Employee

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Official Response
Trying clearing your preference file. Lightroom will rebuild it on startup. You can find the location of the preference file documented here: