A prerequisite perhaps?
For example, I have the problem of adding a new transport protocol to a device.
A prerequisite of that is to make the segmentation threshold at the client end adjustable, and a prerequisite of that is to install the tools that will let me build the client.
english.stackexchange.com/users/None/
One term I’ve heard used for this sort of thing is dependencies .
This comes from a common geekspeak etymological process:
imagine you were a computer program; then, what technical programming term would apply to this situation?
I’d imagine that most programmers would grok this pretty quickly, while most people without programming experience would need an explanation.
So whether it is appropriate would depend a lot on whom you’re trying to communicate with.
english.stackexchange.com/users/2587/PLL
I think I would simply call it a sub-problem .
(If the problem is mathematical, there is a specific term for it; lemma .)
english.stackexchange.com/users/184/Noldorin
I like "roadblock" or "stumbling block" for that sort of thing.
english.stackexchange.com/users/2490/Hellion
My preferred term is a "threshold issue.
" You can't go through until you cross the threshold (resolve the issue).
english.stackexchange.com/users/2707/bikeboy389
I consistently use “ bottleneck issue” (or “bottleneck result”) to describe this: you have no way around it to reach your goal.
In particular, in technical reports and research planning, I commonly read references to “technological bottlenecks”, i.e. key technologies (or components thereof) that need to be worked out for a full solution to be implemented.
english.stackexchange.com/users/3479/F'x
Besides the "prerequisite" I use "blocking step" and precondition
english.stackexchange.com/users/3085/Gennady Vanin Геннадий Ванин
I use the term secondary problem.
Secondary work is often used to describe tasks in the way you are mentioning problems.
i.e. I want to wrap a package, but first I have to find the scissors.
Whether you are describing the thing as a problem to be solved, or a task to do, I find secondary, tertiary, etc.
useful to convey that Im working on something, but one level removed from my ultimate goal.
Another term I use is 'blocking' or 'masking'.
In dealing with computer programming issues, you often find yourself revealing layers of issues.
As you resolve issue, a second issue might arise because you a) got further into the program or b)there was some sort of ripple effect.
You could say issue1 was a blocking issue.
Issue2 was not found until Issue1 was resolved.
english.stackexchange.com/users/33194/greg
Taken to an extreme you get " yac shaving ", but that does not apply only one or two levels in, and may not be understood by non-hacker audiences without some explanation.
In more general managerial contexts you might use the phrase "critical-path issue", but it is a bit of a mouthful and sounds like it is wearing a suit.
This also carries some implication about timing requirements: not only is it required, but it needs addressing before any other absolute requirements.
english.stackexchange.com/users/2851/dmckee --- ex-moderator kitten
Speaking metaphorically, your “problemettes” might be: hurdles to be crossed hoops to be jumped through obstacles to be cleared on your way to the finishing line.
english.stackexchange.com/users/2988/Brian Nixon
There is a huge variety of "stuff that needs to be done in order to do other stuff".
Some of those very specific things (which are not at all synonymous with each other): trailblazing surveying researching planning documenting groundwork legwork prep work capital acquisition parts acquisition building a jig, building a stencil, building a template, building a skeleton sub-assembly training barn-raising sowing the seed watering the seed pruning setup "laying a foundation" (
Whether we pour cement to make a house foundation, or drive piles to make a foundation for a bridge across a stream, we use this phrase -- I can't recall ever hearing "pouring a foundation" or "driving a foundation").
scaffolding dry run spike solution splitting (before burning a tree in a fireplace, it must be split into small pieces) "sharpening the saw" While most of these words and phrases describe some specific literal task in the early stages of farming, roadwork, and building construction, many of them are also used as a metaphor for analogous tasks in other fields, or a synecdoche for all the preparatory work in general.
english.stackexchange.com/users/5510/David Cary
I call them dominoes , as in there is always some other domino / problem to knock over / solve before you get to the main one.
english.stackexchange.com/users/2944/John Satta
The term I hear most often is showstopper .
EDIT
OK, after reading some responses and thinking of this question I'm going to coin a portmanteau.
These problems are prequirements .
;-)
english.stackexchange.com/users/1871/ghoppe
Not a single word, but this is at least related to a "Critical Event chain."
english.stackexchange.com/users/597/MickeyfAgain_BeforeExitOfSO
In [software] engineering, such a problem is called a Blocker
english.stackexchange.com/users/23834/New Alexandria
If I have to solve other problems before getting to the one I want to/have to focus on, I generally just call them steps: "
step 1," "step 2," etc..
english.stackexchange.com/users/23/kitukwfyer
In French they sometimes talk about "le ticket d'entrée" - but that's more to do with the up-front cost of learning a new technology (before benefiting from any - hypothetical - productivity gains).
Down-payment ?
Pinched from another domain, but it might fly.
Though it implies money more than work.
Meta-problem ?
(Meta as in 'before').
I think there is probably a difference to be made between 'drudge/donkey work' (setting up IDE, etc.) and a 'real' up-front problem (something that requires the same level of problem-solving as the actual problem to be solved).
Maybe that though will inspire some more answers...
english.stackexchange.com/users/529/Benjol
See sine qua non , defined by Cambridge dictionary as a necessary condition without which something is not possible.
english.stackexchange.com/users/71659/vickyace
I work in the computer trade and frequently find that when I'm assigned a problem to solve, it invariably happens that other problems need solving before I can work on the real issue. Is there a word for these on-the-way problems?
Is there a word meaning a problem that has to be solved in order to work on another problem?
english.stackexchange.com
<single-word-requests>
english.stackexchange.com/questions/9108
english.stackexchange.com/users/305/Brian Hooper
There does not appear to be an agreed term for these types of problems, but some appropriate terms might include "prerequisite", "dependency" "sub-problem" or "stumbling block". There are  a huge variety of terms that can be used and some have metaphorical value; like "roadblock, sub-problem, threshold issue, bottleneck issue etc." It is a matter of personal choice.
There does not appear to be an agreed term for these types of problems, but some appropriate terms might include "prerequisite", "dependency" "sub-problem" or "stumbling block". Various terms can be used, including "prerequirements; blocking steps; dependencies; threshold issues; bottlenecks; sub-problems or secondary problems; or dominoes.  "Sine qua non" is a more formal expression of a necessary condition without which something is not possible.  
This could be referred to as a sub-problem; a prerequisite; a dependency; a stumbling block; a threshold issue; a bottleneck issue; a secondary problem; a blocking or masking issue; a critical path issue; a domino; a showstopper; or a blocker. In addition, the term "sine qua non" is defined by the  Cambridge dictionary  as  a necessary condition without which something is not possible.    There appears to be no agreed term for this concept, but potential terms for such problems include "prerequisite", "stumbling block", "showstopper" or "blocker".
Taken to an extreme you get " yac shaving ", but that does not apply only one or two levels in, and may not be understood by non-hacker audiences without some explanation.
Taken to an extreme you get " yac shaving ", but that does not apply only one or two levels in, and may not be understood by non-hacker audiences without some explanation.
A  prerequisite  perhaps?  Dependencies Sub-problem  I like "roadblock" or "stumbling block" for that sort of thing. threshold issue. “ bottleneck  issue” ( secondary problem many metaphors can apply S0: There is a huge variety of "stuff that needs to be done in order to do other stuff". S1: Some of those very specific things (which are not at all synonymous with each other):   trailblazing  surveying  researching  planning  documenting  groundwork  legwork  prep work  capital acquisition  parts acquisition  building a jig, building a stencil, building a template, building a skeleton  sub-assembly  training  barn-raising  sowing the seed  watering the seed  pruning  setup  "laying a foundation" ( S2: Whether we pour cement to make a house foundation, or drive piles to make a foundation for a bridge across a stream, we use this phrase -- I can't recall ever hearing "pouring a foundation" or "driving a foundation").   S3: scaffolding  dry run  spike solution  splitting (before burning a tree in a fireplace, it must be split into small pieces)  "sharpening the saw"   While most of these words and phrases describe some specific literal task in the early stages of farming, roadwork, and building construction, many of them are also used as a metaphor for analogous tasks in other fields, or a synecdoche for all the preparatory work in general. dominoes S0: I call them  dominoes , as in there is always some other domino / problem to knock over / solve before you get to the main one. showstopper S0: The term I hear most often is  showstopper .   prerequirements. S2: OK, after reading some responses and thinking of this question I'm going to coin a portmanteau. S3: These problems are  prequirements . In Software engineering, they use blocker Just use "steps" Use of sina qua non
Various terms can be used, including "prerequirements; blocking steps; dependencies; threshold issues; bottlenecks; sub-problems or secondary problems; or dominoes.   "Sine qua non" is a more formal expression of a necessary condition without which something is not possible.   
There appears to be no agreed term for this concept, but potential terms for such problems include "prerequisite", "stumbling block", "showstopper" or "blocker".