Merge conflicts why they happen in Git - Step-by-Step Execution

Process Flow - Merge conflicts why they happen

Start with Branch A and Branch B

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Both branches change same file

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Git tries to merge changes

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Check if changes overlap

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Merge conflict

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User resolves conflict

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Merge completes

This flow shows how merge conflicts happen when two branches change the same part of a file and Git cannot automatically combine them.

Execution Sample

Git

git checkout branchA
# edit file.txt: change line 3
git commit -am "Change line 3 in branchA"

git checkout branchB
# edit file.txt: change line 3 differently
git commit -am "Change line 3 in branchB"

git checkout branchA
git merge branchB

This sequence shows two branches changing the same line in a file, then trying to merge, causing a conflict.

Process Table

Step	Branch	File Change	Git Action	Result
1	branchA	Change line 3 in file.txt	Commit	Change saved in branchA
2	branchB	Change line 3 differently in file.txt	Commit	Change saved in branchB
3	branchA	No change	Checkout branchA	Switched to branchA
4	branchA + branchB	Conflicting changes on line 3	Merge branchB into branchA	Merge conflict detected
5	branchA	User edits file.txt to fix conflict	Resolve conflict manually	Conflict markers removed
6	branchA	No conflict	Commit merge	Merge completed successfully

💡 Merge stops at conflict because Git cannot auto-merge overlapping changes.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 4	After Step 5	Final
file.txt line 3 content	Original line 3	Changed by branchA	Changed differently by branchB	Conflict markers added	Conflict resolved by user	Merged final content

Key Moments - 3 Insights

Why does Git stop the merge at step 4?

Git stops because both branches changed the same line differently, so it cannot decide which change to keep automatically (see execution_table step 4).

What does the user do to fix the conflict?

The user edits the file to choose or combine changes, removing conflict markers before committing (see execution_table step 5).

Why is it safe to commit after resolving conflicts?

Because the user manually fixed the overlapping changes, so the file is now consistent and ready to be merged (see execution_table step 6).

Visual Quiz - 3 Questions

Look at the execution table, what happens at step 4?

A User commits changes

B Git automatically merges changes

C Git detects a merge conflict

D Branch is deleted

💡 Hint

Check the 'Result' column at step 4 in the execution_table

At which step does the user fix the conflict?

A Step 2

B Step 5

C Step 4

D Step 6

💡 Hint

Look for 'User edits file.txt to fix conflict' in the Git Action column

If branchB changed a different line than branchA, what would happen at step 4?

A Merge completes automatically

B User must resolve conflict

C Merge conflict detected

D Merge is aborted

💡 Hint

Refer to the 'No' branch in the concept_flow after 'Check if changes overlap'

Concept Snapshot

Merge conflicts happen when two branches change the same part of a file.
Git tries to merge but stops if changes overlap.
User must manually fix conflicts by editing the file.
After resolving, commit to complete the merge.
Avoid conflicts by communicating and pulling often.

Full Transcript

Merge conflicts occur when two branches change the same line or part of a file differently. Git tries to merge changes automatically but stops if it cannot decide which change to keep. This is called a merge conflict. The user must open the file, see conflict markers, and edit the file to fix the conflict. After fixing, the user commits the changes to complete the merge. This process ensures the final file has consistent content from both branches.