Elon Musk once again tried to launch a paid subscription for Twitter on Monday, after a first attempt marred confusion and the influx of fake accounts.
The social media platform unveiled details online as the day progressed, explaining on its site that the subscription would initially only be available in the US, Canada, Australia, New Zealand and the UK.
But at around 19:00 CET it still did not seem possible to subscribe.
The paid subscription, known as Twitter Blue, has been one of Musk's flagship ideas since taking over the platform in October.
Costing approximately 8 euros per month (11 for Apple users), it will allow users to verify the authenticity of their account with a blue tick, alongside promoting their content in people's searches, seeing fewer adverts and posting longer videos.
Previously blue ticks were reserved for accounts belonging to officials or notable people in certain professional fields, such as journalism, sport or entertainment.
Twitter says on its website the tick may take time to appear to ensure a review that subscribers "meet all the requirements".
Musk's main motivation is to increase the profitability of the platform, which has lost money for eight years of the past decade, though the billionaire has said he also wanted to end the "lord and peasants" verification system, which excluded many people from getting the blue tick.
Critics have said the purpose of verification is undermined if it can be bought, potentially making it more difficult for people to tell what accounts are genuine and exposing them to more misinformation.
The new service will include other features, such as custom app icons, more themes and an 'undo Tweet' function.
Rather than allow Tweets to be edited, it will allow subscribers to retract Tweets after they have been sent, but only before a certain period.
Only Twitter accounts created more than 90 days ago can sign up for Twitter Blue and subscribers must confirm their phone number, Twitter wrote on its web page explaining the new service.
They must also have been active at least once in the previous month and not changed their profile picture or name on Twitter during the previous week.
The social media platform said it is piloting a new service called Twitter Blue for Business, which entitles companies to add a gold checkmark to their official accounts.
Users who already have a tick can keep it without paying, according to the Twitter webpage.
It says the social media giant has the right to remove a user's blue checkmark at any time without offering a refund, should they violate the company's terms or their account is suspended, it adds.
The first attempt to launch the new subscription formula in November was chaotic, with many accounts popping up that posed as celebrities and large companies or spread disinformation.
The project was suspended and then postponed several times.