The most common mistakes when developing apps and how to avoid them

The most common mistakes made when developing applications do not stem solely from problems in the code. They often begin earlier: with an unclear objective, poorly chosen features and an interface that makes it difficult for the user to complete a task. In mobile and web applications, security vulnerabilities and testing only just before launch have similar consequences. The idea itself and efficient implementation are not enough. What also matters is whether the user quickly understands how to use the application and whether their data remains protected. In this article, you’ll learn about common pitfalls relating to interface design, security and testing, as well as specific ways to mitigate risks. You’ll also find out why it’s worth checking the app whilst it’s still being developed, testing it under various conditions, and planning its development with the real needs of users in mind.

Key findings

• Start by considering users’ needs and plan a straightforward path through the app before you start coding.
• Take data protection into account right from the design stage, including the secure processing of information entered by users.
• Test the app under various conditions, including poor connectivity, service interruptions and low battery levels.
• Test the functionality of forms, the layout on different screens and the performance of the web application before deployment.

Table of Contents

• 1. Designing an intuitive UI and a positive UX
• 2. Protection against SQL injection, XSS and CSRF
• 3. Interrupt, background operation and low battery tests
• 4. The most common mistakes when developing web applications
• Internet Stars

1. Designing an intuitive UI and a positive UX

Mistakes in app development often stem from a design that overlooks the everyday needs of the users. Before you create the first screen, identify who will be using the app and what problem it is intended to solve. Then, define the business objective and the features required for the first version. If, for example, a user needs to place an order quickly, plan a short path from product selection to confirmation. A mock-up will show the layout, whilst a prototype will allow you to assess the user flow before you start coding.

How can you plan the development of an app step by step to avoid mistakes? Describe the problem and the target audience, define the features, prepare wireframes and a prototype, and then test it with users. Use the feedback you’ve gathered to refine the design and the schedule. Repeat usability tests at subsequent stages. This will enable the team to correct any unclear elements before changes to them affect multiple screens.

Unintuitive navigation means the user has to guess what to do next. A cluttered screen, an unclear icon or inconsistent labelling make the app difficult to use. If the shopping basket in an online shop is hidden behind an illegible symbol, it is hard to find. You can minimise such errors when developing an app by using buttons with clear labels and concise messages. Instead of writing ‘validation error’, highlight the field that needs correcting. Complement the colour with text: red can signal a problem, green a successful result, and yellow a warning.

What regulations in Poland and the EU must the app comply with, including the GDPR and accessibility requirements? Where the app processes personal data, ensure compliance with the GDPR and data protection at every stage of the data flow. Support accessibility through clear contrast, element labels and keyboard navigation.

Design with different devices and usage scenarios in mind. Check how the web application looks on a narrow screen, and ensure the mobile app complies with iOS and Android standards. Explain navigation gestures with a brief tip. In an AI app, specify what data it accepts and in what format it should return responses. Before any irreversible action is taken, display the result for approval, and provide sources for factual responses. Test with your audience and improve the areas where they get stuck.

2. Protection against SQL injection, XSS and CSRF

An attack may begin with a simple login form. SQL injection involves injecting commands into a database query that the application should not execute. Use parameterised queries and validate input data on the server side. Do not construct queries by concatenating text with form content. This ensures that the entered data remains just data, rather than part of a database command.

Cross-Site Scripting, or XSS, allows a malicious script to be embedded in content displayed to other users. For example, if an application displays a comment without properly escaping characters, the browser may interpret it as code. Sanitise content and encode data when displaying it. CSRF, on the other hand, exploits an active user session to send an unauthorised request. Mitigate this risk by using security tokens and appropriate cookie settings.

Before launch, check the security of web and mobile applications, rather than limiting yourself to functional testing. Verify the login process, account recovery, role-based permissions and how the application behaves following an incorrect password. Use HTTPS, encrypt personal data and passwords, and update your libraries. Prepare test scenarios for different devices, platforms and accounts with varying permissions. Security testing should also cover unexpected data entered into forms.

• Input data: check the login fields, comments and forms.
• Access: ensure that a user’s account does not grant access to other people’s data.
• Connection: check whether the app uses HTTPS.
• Libraries: fix known vulnerabilities by applying updates before deployment.

Before releasing an AI application, define the permitted inputs and the expected response format. Prepare a set of 30–100 test cases covering typical questions, misleading data and high-risk requests. Ensure that a human approves the result before any irreversible action is taken. For factual responses, cite your sources. Restrict access to logs and limit their retention period, and keep test environments separate from the production environment. Such measures help to detect errors before users are affected. If you are planning to develop an application, incorporate security checks into the process from the outset.

SQL injection, cross-site scripting (XSS) and cross-site request forgery (CSRF) are threats that can cause serious harm to a company and its customers. It is therefore worth taking them into account in security measures.

3. Interrupt, background operation and low battery tests

A mobile app should maintain continuity of operation when the user puts their phone down for a moment. Check what happens when a call is answered, the screen is locked, or the user switches to another app. Upon returning, the user should be able to continue with their task. Test, for example, a partially completed form and the resumption of paused content. Such scenarios will show whether the app retains its state without needing to restart the entire process.

A low battery level may restrict the operation of background processes. Check that the app saves data and completes any tasks it has started without freezing. Monitor memory and processing power usage during tasks such as sending a photo. Also test older devices with fewer resources. It is easier to detect errors in app development when tests take hardware limitations into account, rather than just the conditions on a new phone.

Do not test exclusively on a stable Wi-Fi connection. Simulate poor signal strength, a loss of internet connection whilst submitting a form, and reconnection. Check whether the app notifies the user of an interruption and does not repeat the action without the user’s knowledge. Take into account different screen sizes, amounts of RAM and the processing power of devices. Testing under such conditions helps to minimise errors during app development before they hinder day-to-day use.

Run tests at the start of development and following changes that may affect existing functionality. Regression testing repeats recorded scenarios, such as logging in, making a purchase and password recovery. Also include edge cases: an empty field, very long text or an interrupted file upload. In an AI application, check for incomplete data and situations requiring human approval of responses. Repeating tests after changes minimises errors during application development and allows you to spot undesirable effects more quickly.

What are the most common mistakes made when testing and deploying apps? They include testing only the main flow, overlooking glitches, and postponing testing until launch. Technical issues are the reason 11 per cent of users uninstall an app. Before deployment, carry out functional, performance and security tests. After publication, analyse reports and rectify any issues identified.

4. The most common mistakes when developing web applications

A web application may work correctly when traffic is low, but slow down as the number of users increases. Common sources of problems include numerous database queries, uncompressed images and JavaScript files. Minimise unnecessary reads, reduce the amount of data sent to the browser, and identify which operations are putting a strain on the server. Caching and a content delivery network can reduce loading times when users connect from different locations.

Architecture hinders development when every new feature requires changes to multiple parts of the system. One example is an order module that is directly dependent on payment code and user accounts. Separate areas of responsibility, describe the data flow and determine how systems exchange information. According to Gov.pl, changes to the API on the provider’s side require changes on the recipient’s side and may not be signalled sufficiently in advance. Plan for integration errors, rather than assuming that every connection will always work.

What technical and architectural flaws hinder application development? The most common are rigid dependencies between modules, a lack of control over queries, and ill-conceived data storage in memory. These can slow down the application, make it difficult to add features and increase the risk of failure. You should also ensure that the layout adapts to different screens, not just the designer’s monitor.

What mistakes cause an app development project to go over budget and miss its deadline? An unclear scope, frequent changes in priorities and postponing testing until the very end lead to fixes across multiple modules. Before starting work, define the features of the first release, technical dependencies and acceptance criteria. Divide development into stages, and test each release for functionality, performance and load. Choose tools based on the scale of the project, not on their current popularity.

Use this guide as a starting point: first, identify which web features are hindering development, then map out their interdependencies. If you are planning to build or refactor an application, discuss the web application design and plan its development in stages.

It is equally important to design a web application with different devices and screen sizes in mind, as well as the growing number of users, without compromising performance. In forms, increase error tolerance, make validation more flexible and limit the possibility of submitting a form with incorrect data.

Test your app at an early stage to quickly identify and fix issues. Manual testing with every update is time-consuming and prone to errors, whilst automated testing can reduce the time taken to detect bugs and minimise the cost of fixing them. Before launch, check that the app is working correctly to minimise the risk of users having a negative first impression.

Internet Stars

Internet Stars helps translate a company’s needs into digital solutions that address users’ specific problems. Whether you’re planning an app or want to organise its development, our team can support your project – be it a bespoke app, an online shop or an automation solution. Start by defining the objective, the features of the first version and how you’ll test the app’s functionality.

Collaboration is particularly useful when bugs recur after successive deployments, when development is held up by interdependencies between features, or when there is no shared plan for the business and the technical team. Internet Stars also runs training courses to help teams better understand the solutions they are developing and use them more effectively. Choose the area that is currently posing the greatest obstacle to development and describe it during your consultation.

Please contact Internet Stars to discuss your project.

Turn your idea into the next step

A good application evolves alongside the company and its users. So decide what outcome you want the next version to deliver: faster order processing, easier access to the service, or more efficient teamwork. A clearly defined goal will help you set priorities and assess whether further changes support the business. It is easier to minimise errors during app development when design and technical decisions are guided by a single, clearly defined direction.

If you’re planning a new app or want to develop an existing solution, get in touch with the Internet Stars team. The company has been in business since 2008, and its team can help translate your project objectives into a plan for the next steps. Start by describing the challenge you want to tackle and your expectations for the application. Contact Internet Stars to work out which next step is best suited to your project.

Frequently Asked Questions

What are the most common mistakes made when developing mobile apps, and how can they be avoided?

A common problem is starting work without establishing how the result will be assessed. Set out specific acceptance criteria for each feature, for example: the user can save a sketch and return to it after restarting. Also, establish who approves product and technical decisions. Clear rules minimise the need for revisions arising from differing expectations amongst those involved in the project.

Error 2: How can you build a device matrix rather than testing on a single phone?

Start with data on the devices used by your customers, then select representative combinations of operating systems and hardware. In the matrix, record the model, operating system version, installation method and the scenario to be tested. You do not need to test every combination with every change. Select a core set for day-to-day testing, and run the remaining devices when testing features that depend on the hardware.

Error 3: Why is the visual layer alone not enough?

The mock-up does not show all the states that the user will encounter. Describe how the screen behaves whilst loading, when there are no search results, and after double-clicking the button. For example, when the server responds slowly, the application should indicate that it is still processing the request. Such scenarios help to verify whether an attractive design goes hand in hand with predictable behaviour.

Mistake 4: What are you overlooking in your installation and update tests?

Check whether the update preserves user settings and correctly transfers saved data to the new version. Also test the scenario where the installation is interrupted or the user denies the permission required for a particular function to work. If permission is denied, the application should still allow the user to use the remaining parts. Record these cases as separate scenarios to be repeated in future releases.

Mistake 5: How can you check security without carrying out a penetration test with every release?

Determine which changes require an additional security review. Changing the login method, adding new user roles or altering the flow of data between systems may have a greater impact on the risk profile than a textual correction. For minor changes, carry out regular code reviews and dependency checks, and schedule a more thorough assessment following major architectural changes. Document decisions and the reasoning behind them so that the team knows what has been checked.

Mistake 6: How do you set priorities when it’s impossible to test everything?

Assess each scenario in terms of the impact of a failure, the number of people it might affect, and the difficulty of detecting the problem once it has been implemented. A failure in report export can wait if it does not block work, but an error in order calculation requires immediate investigation. Save the highest-rated cases as a permanent checklist. Plan the rest in line with changes in future releases and user reports.

An article by

Andrzej Klimek

Owner of Internet Stars since 2008