1+ # Github PowerShell error documentation:
2+ # https://github.com/MicrosoftDocs/PowerShell-Docs/issues/1583
3+ 4+ # Primary Pipeline aka output stream aka success pipeline
5+ # error pipeline
6+ 7+ # -------------------------------------------------
8+ # non-terminating error
9+ 1 / 0 ; Write-Host ' Hello, will I run after an error?'
10+ 11+ # non-terminating errors don't stop loops
12+ $collection = @ (
13+ ' C:\Test\newcsv.csv' ,
14+ ' c:\nope\nope.txt'
15+ ' C:\Test\newcsv2.csv'
16+ )
17+ foreach ($item in $collection ) {
18+ Get-Item $item
19+ }
20+ # -------------------------------------------------
21+ # terminating errors
22+ 23+ # Without ErrorAction
24+ Get-Item - Path c:\nope\nope.txt; Write-Host ' Hello, will I run after an error?'
25+ # With ErrorAction
26+ Get-Item - Path c:\nope\nope.txt - ErrorAction Stop; Write-Host ' Hello, will I run after an error?'
27+ 28+ # try/catch/finally
29+ # https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_try_catch_finally?view=powershell-6
30+ 31+ # throw causes PowerShell to terminate
32+ try {
33+ 1 / 0 ; Write-Host ' Hello, will I run after an error?'
34+ }
35+ catch {
36+ throw
37+ }
38+ 39+ # this example will not go the catch and will run the Write-Host
40+ try {
41+ Get-Item - Path c:\nope\nope.txt; Write-Host ' Hello, will I run after an error?'
42+ }
43+ catch {
44+ Write-Host ' You are now in the catch'
45+ }
46+ 47+ # this example will error and go directly to the catch
48+ try {
49+ Get-Item - Path c:\nope\nope.txt - ErrorAction Stop; Write-Host ' Hello, will I run after an error?'
50+ }
51+ catch {
52+ Write-Host ' You are now in the catch'
53+ }
54+ 55+ 56+ $processNames = @ (
57+ ' NotAProcess' ,
58+ ' Notepad'
59+ 60+ )
61+ foreach ($item in $processNames ) {
62+ try {
63+ Get-Process - Nam $item
64+ }
65+ catch {
66+ Write-Host $item
67+ throw
68+ }
69+ }
70+ 71+ # Write-Error simply prints the error for the user
72+ try {
73+ 1 / 0 ; Write-Host ' Hello, will I run after an error?'
74+ }
75+ catch {
76+ # Maybe Log Something Right here
77+ Write-Error $_
78+ }
79+ 80+ # Finally will log results regardless of what happens
81+ try {
82+ Get-Content - Path c:\nope\nope.txt - ErrorAction Stop
83+ }
84+ catch {
85+ Write-Error $_
86+ }
87+ finally {
88+ # log results to a logging file
89+ }
90+ # -------------------------------------------------
91+ 92+ # The website exists, but the page does not
93+ try {
94+ $webResults = Invoke-WebRequest - Uri ' https://techthoughts.info/nope.htm'
95+ }
96+ catch {
97+ Write-Error $_
98+ }
99+ 100+ # The website exists, but the page does not
101+ try {
102+ $webResults = Invoke-WebRequest - Uri ' https://techthoughts.info/nope.htm'
103+ }
104+ catch {
105+ $theError = $_
106+ if ($theError.Exception -like " *404*"
107+ Write-Warning ' Web page not found. Check the address and try again.'
108+ # Retry code
109+ }
110+ else {
111+ throw
112+ }
113+ }
114+ 115+ # The website does not exist
116+ try {
117+ $webResults = Invoke-WebRequest - Uri ' https://techthoughtssssssss.info/'
118+ }
119+ catch {
120+ $theError = $_
121+ $theError.Exception
122+ }
123+ 124+ # The website exists, but the page does not
125+ try {
126+ $webResults = Invoke-WebRequest - Uri ' https://techthoughts.info/nope.htm'
127+ }
128+ catch {
129+ $theError = $_
130+ # see all the sub-properties
131+ $theError | Format-List * - Force
132+ }
133+ 134+ # -------------------------------------------------
135+ # $Error
136+ 137+ $Error
138+ 1 / 0 ; $Error
139+ Get-Process - Name ' NotAProcess'
140+ $Error
141+ $Error.Clear ()
142+ 143+ $Error [5 ] | Format-List * - Force
144+ # -------------------------------------------------
145+ 146+ # this example will help display some helpful message to the user
147+ # this example will only work in PowerShell 6.1+
148+ $uri = Read-Host ' Enter the URL'
149+ try {
150+ $webResults = Invoke-WebRequest - Uri $uri - ErrorAction Stop
151+ }
152+ catch {
153+ $statusCodeValue = $_.Exception.Response.StatusCode.value__
154+ switch ($statusCodeValue ) {
155+ 400 {
156+ Write-Warning - Message " HTTP Status Code 400 Bad Request. Check the URL and try again."
157+ }
158+ 401 {
159+ Write-Warning - Message " HTTP Status Code 401 Unauthorized."
160+ }
161+ 403 {
162+ Write-Warning - Message " HTTP Status Code 403 Forbidden. Server may be having issues. Check the URL and try again."
163+ }
164+ 404 {
165+ Write-Warning - Message " HTTP Status Code 404 Not found. Check the URL and try again."
166+ }
167+ 500 {
168+ Write-Warning - Message " HTTP Status Code 500 Internal Server Error."
169+ }
170+ Default {
171+ throw
172+ }
173+ }
174+ }
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