November 2020
So, i dunno who needs to hear this.
New install on a new computer, a few friends of mine were reminiscing over old ME3 days. I could do absolutely nothing to fix this, i looked through this thread and one other. I noticed that i actually had no folder in My Documents. I figured, given my hard drive is partitioned it might perhaps have installed somewhere else? Nothing.
Ultimately, i had to go into Game Properties in Origin, go to Cloud Saves, and restore a local backup to essentially make the game realize it didn't have one.
The downside of this is that I have no ME3 save files anymore. This isn't a big deal to me as they were all at least 4 years old, but it fixed my problem with the CtD, so. Here it is.
November 2020 - last edited November 2020
Here this will works. He just described the problem well and fixes the bug. Even if it is not a problem of dlc itself, it also helps https://answers.ea.com/t5/Mass-Effect-3/Retaliation-DLC-Crash/td-p/354722/page/3
I'll just add a few sentences from myself: If you use ALOT or other Project Variety 3 mods install them first then this patch.