Problem with merging catalogs

[fcukn12075629]

Hello,

I have 4 different catalogs, all on an external harddrive. I am currently trying to combine those into one "big" master catalog. Every time I try this, there appears the following message: "Right now an import out of this catalog isn't possible. It wasn't possible to create a functioning temporary copy of this catalog." (Translated from german...) This message appears immediately, it doesn't start doing anything else.

What might be the problem - and the solution?

Background info:

- I'm using Lightroom 5 on Windows

- The 4 catalogs are aprox. 700 GB, consisting out of 45'000 pictures

[Mohit Goyal]

Hi fcukn,

We're really for all the trouble. Does all 4 catalogs created in Lightroom 5?

Could you please post the screenshot of the error message?

Regards,

Mohit

[JohanElzenga]

Sounds like that external hard drive may not be writable for Lightroom. And make sure it's a local hard drive, not a NAS.