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SEO issue types - All detectable problems explained

Missing title tag

criticalmeta

Page has no title tag

1

Invalid JSON in structured data

criticalstructured data

Structured data contains invalid JSON syntax

2

4XX client error

criticaltechnical

Page returns 4XX HTTP status code

3

5XX server error

criticaltechnical

Page returns 5XX HTTP status code

4

No SSL certificate

criticaltechnical

Page is not served over HTTPS

5

Homepage missing from sitemap

criticaltechnical

The website homepage (root URL) is not included in the sitemap

6

Duplicate title

highmeta

Multiple pages share the same title tag

7

Missing meta description

highmeta

Page has no meta description

8

Canonical URL mismatch

highmeta

Canonical URL points to a different page than expected

9

Missing meta viewport

highmeta

Page has no viewport meta tag

10

Missing H1 tag

highcontent

Page has no H1 heading

11

Empty H1 tag

highcontent

H1 tag exists but has no text content

12

Invalid structured data

highstructured data

Structured data has syntax errors

13

Structured data missing @type

highstructured data

Structured data object is missing @type property

14

Required structured data type missing

highstructured data

Page is missing a required structured data type for its content

15

Not mobile friendly

hightechnical

Page lacks viewport meta tag

16

Title not in document head

highmeta

The page title is not in the HTML head; we found a title elsewhere (e.g. in the body). Search crawlers typically only read the head.

17

Title too short

mediummeta

Title is less than 55 characters

18

Meta description too short

mediummeta

Meta description is less than 120 characters

19

Duplicate meta description

mediummeta

Multiple pages share the same meta description

20

Missing canonical tag

mediummeta

Page has no canonical URL specified

21

HTML lang and OG locale mismatch

mediummeta

HTML lang attribute and og:locale meta tag do not match

22

Multiple H1 tags

mediumcontent

Page has more than one H1 heading

23

Missing H2 tag

mediumcontent

Page has no H2 heading

24

Empty H3 tag

mediumcontent

H3 tag exists but has no text content

25

No internal links

mediumcontent

Page has no internal links to other pages

26

Missing OG title

mediumog

Page has no og:title meta tag

27

Missing OG description

mediumog

Page has no og:description meta tag

28

Missing OG image

mediumog

Page has no og:image meta tag

29

OG image invalid dimensions

mediumog

og:image does not meet minimum dimensions (1200x630)

30

OG image not accessible

mediumog

The og:image URL cannot be fetched (returns error, timeout, or non-200 status)

31

Product schema missing price

mediumstructured data

Product schema lacks price information

32

Product schema missing image

mediumstructured data

Product schema lacks image property

33

Article schema missing date

mediumstructured data

Article schema lacks datePublished

34

Article schema missing author

mediumstructured data

Article schema lacks author property

35

Structured data type does not exist

mediumstructured data

Specified schema type is not a valid schema.org type

36

Important internal link is nofollow

mediumlinks

High-value internal link has rel="nofollow"

37

Slow page load

mediumtechnical

Page takes more than 3 seconds to load

38

Image missing alt text

mediumimages

Image lacks alt attribute

39

Non-HTML content type

mediumtechnical

This URL returns a non-HTML content type. Standard XML sitemaps should only contain URLs that serve HTML pages. Non-HTML resources like images, PDFs, or JSON files should use dedicated sitemap extensions or be removed.

40

Structured data disconnected groups

mediumstructured data

Structured data entities form multiple disconnected groups instead of one linked graph

41

Title too long

lowmeta

Title exceeds 60 characters and will be truncated in search results

42

Meta description too long

lowmeta

Meta description exceeds 160 characters

43

Missing favicon

lowmeta

Page has no favicon (icon link tag)

44

Missing Apple touch icon

lowmeta

Page has no Apple touch icon link tag

45

Missing web app manifest

lowmeta

Page has no manifest link tag

46

H1 too long

lowcontent

H1 exceeds 70 characters

47

H2 too long

lowcontent

H2 exceeds 70 characters

48

H3 too long

lowcontent

H3 exceeds 60 characters

49

Broken heading hierarchy

lowcontent

Headings skip levels (e.g., H2 → H4)

50

OG image wrong size

lowog

og:image aspect ratio is not optimal (recommended 1.91:1 ratio, e.g., 1200x630px)

51

OG image missing alt text

lowog

og:image has no og:image:alt attribute

52

Missing Twitter card

lowog

Page has no twitter:card meta tag

53

Missing Twitter image

lowog

Page has no twitter:image meta tag

54

Missing OG locale

lowog

Page has no og:locale meta tag

55

Missing OG type

lowog

Page has no og:type meta tag

56

Missing OG URL

lowog

Page has no og:url meta tag

57

Missing OG site name

lowog

Page has no og:site_name meta tag

58

Missing OG image width

lowog

Page has no og:image:width meta tag

59

OG image width too small

lowog

og:image:width is less than 1200px

60

Missing OG image height

lowog

Page has no og:image:height meta tag

61

OG image height too small

lowog

og:image:height is less than 630px

62

FAQ schema has too few questions

lowstructured data

FAQPage schema should have at least 2 questions

63

Generic anchor text

lowlinks

Internal link uses generic anchor text like "click here" or "read more"

64

Duplicate anchor text

lowlinks

Same anchor text points to multiple different URLs, which can confuse users and search engines

65

Sitemap invalid lastmod format

lowtechnical

Sitemap lastmod value is not in valid date format

66

Sitemap invalid changefreq value

lowtechnical

Sitemap changefreq value is not valid

67

Sitemap invalid priority value

lowtechnical

Sitemap priority value is not between 0.0 and 1.0

68

Image alt text too long

lowimages

Alt text exceeds 125 characters

69

Page set to noindex

infometa

Page has robots meta tag with noindex directive

70

Page set to nofollow

infometa

Page has robots meta tag with nofollow directive

71

Missing meta keywords

infometa

Page has no meta keywords tag

72

Missing link author

infometa

Page has no author link tag

73

Missing H3 tag

infocontent

Page has no H3 heading

74

Thin content

infocontent

Page has less than 300 words

75

Missing OG image type

infoog

Page has no og:image:type meta tag

76

No structured data

infostructured data

Page has no structured data markup

77

Missing breadcrumb schema

infostructured data

Page lacks BreadcrumbList schema

78

Too many links

infolinks

Page has more than 100 links

79

Isolated page

infolinks

Page has no outgoing internal links and does not distribute link equity

80

Over-optimized anchor text

infolinks

Page has multiple links with identical or very similar keyword-rich anchor text (over-optimization)

81

URL too long

infotechnical

URL exceeds 100 characters

82

URL has query parameters

infotechnical

URL contains unnecessary query parameters

83

Sitemap missing lastmod

infotechnical

Sitemap URL entry has no lastmod attribute

84

Sitemap missing changefreq

infotechnical

Sitemap URL entry has no changefreq attribute

85

Sitemap missing priority

infotechnical

Sitemap URL entry has no priority attribute

86

Image format not optimized

infoimages

Images not in WebP, AVIF, or PNG could be replaced for better compression.

87

Outdated year references

infofreshness

Content mentions old years (e.g., 2022, 2023)

88

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