1:46 PM PT -- Despite fans' high hopes, it appears the concert in Manchester's been canceled ... with some sharing a notice they say they received at the venue on X.

1:03 PM PT -- It appears Nicki Minaj's been released from custody ... the police department put out a statement saying it had released a 41-year-old American from custody with just a €350 fine. While again they don't name Nicki, it appears they're referring to her.

Nicki Minaj's flight out of Amsterdam didn't proceed as planned ... 'cause cops detained her on her way to the UK -- and, now, she's seemingly been arrested.

The rapper live streamed her conversation with the authorities Saturday ... and, it starts with a police officer saying she needs to accompany them to a precinct.

Check out the clip ... Nicki asks multiple times for the police station's address while also confused as to why she needs to go with the officers at all. One of the cops tells Nicki they want to get her to her next show on time if they can -- before telling Minaj she's under arrest.

The officers ask Nicki to stop filming them and step into their police vehicle ... while Minaj says she wants to speak with her lawyer and refuses to turn the camera off. Nicki ultimately gets into the police van of her own volition -- no handcuffs as far as we can tell.

Robert Kapel, a spokesperson for Royal Netherlands Marechaussee military police confirmed to TMZ they'd arrested an American woman for possessing "soft drugs" -- like marijuana for example -- and described a similar scenario to Minaj's, but refused to identify her by name or the type of alleged drugs.

Minaj posted another video too ... where a man who appears to be an airport employee tells Nicki the cops need to thoroughly search her bags -- apologizing profusely for the inconvenience.

BTW ... Minaj has tweeted a couple times in the aftermath of the video -- telling her followers the cops say they found weed in her luggage, and letting everyone know her security's already told the officers the weed is his.

Nicki's overseas right now on the European leg of her "Pink Friday 2" tour. She performed in the Dutch city last night and had a show scheduled for this evening in Manchester, England. Doors are set to open at 7:00 PM local time -- so, the venue's still hoping she'll make it it seems.

We've reached out to Nicki's camp ... so far, no word back.