Good morning, I’m NOT new to Manjaro.
The 25.0.1 installer appears to offer the option of manual partitioning. However, if you try that option, the “Next” button is always grayed out. This is no matter how “complete” you appear to have made things.
Did I set up something wrong? Who knows? The installer won’t tell me.
If there is in fact a problem with the partitioning options the user chooses, the installer should show those errors.
Very frustrating, makes me want to move to another distro.
It does indeed.
We can’t know. Only you could, potentially.
For assistance to sort it out, you’d have to detail the steps you took, which lead to the situation where you could not continue.
It probably should.
To find out why it apparently doesn’t, we need to know the route you took (to be able to follow along and see …).
After you select “Manual Partitioning”, there is a “Next” button,
which brings you to the next stage, where you need to create a “New Partition” Table" with the only option available (not greyed out).
Only when this is done, you get the option to “Create” new partitions, specify mount points and so on.
The flow is logically consistent - I see no flaw.
Sounds quite strange …
How exactly did you partition the device? And please no screenshots.
Detail in writing …
The installer framework is Calamares - which is used by many, many distributions - if you have any issues with the installer the best place to raise those is Calamares (official repo) · GitHub.
With a manual partitioning schema the user is in control - and is expected to know how to do it.
Perhaps you forgot to assign a mount point to root partition 
well i haven’t checked it but everything is possible. a clever workaround is to use a distro like gparted, partition the system with it and then use the installer of manjaro by using the option “use existing filesystems”.
p.s.: sometimes nvme’s aren’t detected fully functional. happened to me also once with an samsung. for whatever reason it was recognized with the automated option to use it complete but it wasn’t discovered at manual partitioning.
I’m afraid you haven’t provided nearly enough information for anyone to even guess what your problem is.
However, a quick Internet search found the following linked Calamares User’s Guide which might be helpful.
Research is always a useful tool.
Regards.
I do not trust Calamares for the partitioning because it showed bugs in this department before. Just use Gparted to partition manually and then start the installer and just click the mountpoints there.
Please provide documentation for your statement - otherwise it is unfounded and irrelevant to the topic at hand.
Hi,
Big chance you forgot something like a file system. I did’t notice this at all during the install.
Look at the answer of @linux-aarhus
Manjaro Xfce ISOs include gparted for partitioning drives
Indeed;
@Olli I believe that all of the Manjaro .ISOs have a partition manager available to use from the Live Session. Plasma should have KDE Partition Manager rather than GParted by default.
Far more convenient than booting from two .ISOs. 
I normally use this first, then launch the installer.
GParted has proven itself to be a very reliable partition manager. Unlike other programs, it has been working extremely reliably for years. It manages to handle some situations flawlessly and guide the user safely to the desired result, something some other programs can’t do as well.
If you search the forum for problems during or after partitioning, you’ll find that GParted is the most reliable.
I know some others have reported concerns with KPM; what I actually meant by “should” is that I think this is still the case i.e. Plasma ISOs come with KPM instead of GParted.
I’ll just say that I’ve had no issues with KDE Partition Manager, though.
Out of curiosity I thought I’d give this a try.
I downloaded kde minimal, used virtualbox and thrice I tried manual partitioning - each time a different setup:
Every try succeeded, so without knowing exactly what steps you took, I am afraid you must have overlooked something (or come across some obscure bug).
As off-topic as this might be considered, I often use gdisk (a part of Rod Smith’s GPTFDISK suite of utilities) to achieve the same result.
Using gdisk (to create the partition layout desired) or gparted (for the same purpose) is a handy workaround to avoid potential pitfalls of a native partition manager; whether real or perceived.
That said, the native partitioner should idealy be used when possible; it’s important for users to perform research as needed to fully understand how it works, and reasons why it might not.
Well, it might prevent you from continuing (clicking “Next”), and that surely indicates something wasn’t done right.
The Installer is stupid and can’t predict everything the user might (or might not) do, and neither can we, without a full and detailed description of exact steps taken.
Without that, it is surely;
for those who might wish to help.
As you are;
please post system information as described (below) in case this reveals any potential contributors to your issue.
Regards.
While information from *-fetch type apps might be fine for someone wishing to buy your computer, for Support purposes it’s better to ask your system directly; 
Output of the inxi command with appropriate parameters will achieve this (naturally, formatted according to forum guidelines) and will generally be more useful for those wishing to help:
inxi --filter --verbosity=8
or the short form:
inxi -zv8
You are asking if you set up something wrong. it’s difficult to know if it’s YOU who did something wrong, or perhaps it might be some hardware issue with Calamares.
Now, having asked this question - you would need to help someone work out what the issue actually is. This isn’t reddit, where people are expected to automatically know every step you took, every detail about your system.
You said you are not a new Manjaro user, so you should be familiar with the kind of information required. You made several posts in the past like this:
You simply disappear. Be aware that any other distribution using the Calamares installer is likely to have exactly the same issue.
However, if some minor issue like this is enough to convince you that another distribution would be better, then perhaps it is time to try something new.
There is no rule that states you must use Manjaro - many people here use other distributions (and many people also return to use Manjaro again once they realise the issues they faced were not ‘Manjaro’ specific issues).
If you wish this thread to move forward, I hope you will READ the previous replies to your issue, and then REPLY to people’s attempts to help you… some of these attempts took a deal of thought, and a fair amount of time probably searching/researching to formulate.
In my testing, the installer works perfectly, I cannot replicate this issue (though 1. I’m not testing with a VM and 2. I’m not testing with YOUR setup).
Nor have I. It works fine for me.
GParted has always been considered more mature and battle tested… I kicked back at this some years ago saying that KDE Partition manager became my favourite.
I remember hearing it said that KDE Partition Manager occasionally struggles (with certain operations - resizing BTRFS, or handling NTFS moves) so that GParted is the preferred tool for complex tasks.
The other benefit of GParted is more apparent to anyone not running Plasma - it will have far fewer dependencies… wider support across various documentations/guides etc.
This isn’t backed up by my personal experience though… so it’s quite possibly just a case of echoing problems from the past which have long since been eradicated.
From package lists for other ISOs:
Cinnamon ISOs include gparted
Gnome ISOs have gnome-disk-utility
KDE ISOs do not include partitionmanager, only parted CLI tool
Interesting.
Please note that during the transition from plasma 5 to plasma 6 the calamares installer had a dependency on the plasma5 partitioning library and thus could not include the partition manager with the live ISO.
I think gparted package has been added to the shared Packages-Live package list a long time ago and as such it is included with all live ISO
The KDE iso-profile Packages-Desktop has not yet been reverted to include partitionmanager
It must be this fact @nikgnomic is referring to as all live ISO is using the shared Packages-Live package list and thus all is providing gparted in the live environment - some is also providing it with the final installation.