Ubunut Gnome deployment template failed

The out of the box Ubuntu Gnome template fails in the "UK South" region as the VM Standard_D2 is not available.

{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-debug for usage details.","details":[{"code":"BadRequest","message":"{\r\n \"error\": {\r\n \"code\": \"InvalidParameter\",\r\n \"message\": \"The requested VM size Standard_D2 is not available in the current region. The sizes available in the current region are: Standard_B1ms,Standard_B1s,Standard_B2ms,Standard_B2s,Standard_B4ms,Standard_B8ms,Standard_A0,Standard_A1,Standard_A2,Standard_A3,Standard_A5,Standard_A4,Standard_A6,Standard_A7,Basic_A0,Basic_A1,Basic_A2,Basic_A3,Basic_A4,Standard_D1_v2,Standard_D2_v2,Standard_D3_v2,Standard_D4_v2,Standard_D5_v2,Standard_D11_v2,Standard_D12_v2,Standard_D13_v2,Standard_D14_v2,Standard_D15_v2,Standard_D2_v2_Promo,Standard_D3_v2_Promo,Standard_D4_v2_Promo,Standard_D5_v2_Promo,Standard_D11_v2_Promo,Standard_D12_v2_Promo,Standard_D13_v2_Promo,Standard_D14_v2_Promo,Standard_F1,Standard_F2,Standard_F4,Standard_F8,Standard_F16,Standard_DS1_v2,Standard_DS2_v2,Standard_DS3_v2,Standard_DS4_v2,Standard_DS5_v2,Standard_DS11-1_v2,Standard_DS11_v2,Standard_DS12-1_v2,Standard_DS12-2_v2,Standard_DS12_v2,Standard_DS13-2_v2,Standard_DS13-4_v2,Standard_DS13_v2,Standard_DS14-4_v2,Standard_DS14-8_v2,Standard_DS14_v2,Standard_DS15_v2,Standard_DS2_v2_Promo,Standard_DS3_v2_Promo,Standard_DS4_v2_Promo,Standard_DS5_v2_Promo,Standard_DS11_v2_Promo,Standard_DS12_v2_Promo,Standard_DS13_v2_Promo,Standard_DS14_v2_Promo,Standard_F1s,Standard_F2s,Standard_F4s,Standard_F8s,Standard_F16s,Standard_A1_v2,Standard_A2m_v2,Standard_A2_v2,Standard_A4m_v2,Standard_A4_v2,Standard_A8m_v2,Standard_A8_v2,Standard_D2_v3,Standard_D4_v3,Standard_D8_v3,Standard_D16_v3,Standard_D32_v3,Standard_D2s_v3,Standard_D4s_v3,Standard_D8s_v3,Standard_D16s_v3,Standard_D32s_v3,Standard_D64_v3,Standard_D64s_v3,Standard_E2_v3,Standard_E4_v3,Standard_E8_v3,Standard_E16_v3,Standard_E20_v3,Standard_E32_v3,Standard_E64i_v3,Standard_E64_v3,Standard_E2s_v3,Standard_E4-2s_v3,Standard_E4s_v3,Standard_E8-2s_v3,Standard_E8-4s_v3,Standard_E8s_v3,Standard_E16-4s_v3,Standard_E16-8s_v3,Standard_E16s_v3,Standard_E20s_v3,Standard_E32-8s_v3,Standard_E32-16s_v3,Standard_E32s_v3,Standard_E64-16s_v3,Standard_E64-32s_v3,Standard_E64is_v3,Standard_E64s_v3,Standard_NV6,Standard_NV12,Standard_NV24,Standard_NC6,Standard_NC12,Standard_NC24,Standard_NC24r,Standard_M32-8ms,Standard_M32-16ms,Standard_M32ls,Standard_M32ms,Standard_M32ts,Standard_M64-16ms,Standard_M64-32ms,Standard_M64ls,Standard_M64ms,Standard_M64s,Standard_M128-32ms,Standard_M128-64ms,Standard_M128ms,Standard_M128s,Standard_M64,Standard_M64m,Standard_M128,Standard_M128m,Standard_H8,Standard_H16,Standard_H8m,Standard_H16m,Standard_H16r,Standard_H16mr,Standard_F2s_v2,Standard_F4s_v2,Standard_F8s_v2,Standard_F16s_v2,Standard_F32s_v2,Standard_F64s_v2,Standard_F72s_v2,Standard_M8-2ms,Standard_M8-4ms,Standard_M8ms,Standard_M16-4ms,Standard_M16-8ms,Standard_M16ms,Standard_NC6s_v3,Standard_NC12s_v3,Standard_NC24rs_v3,Standard_NC24s_v3,Standard_G1,Standard_G2,Standard_G3,Standard_G4,Standard_G5,Standard_GS1,Standard_GS2,Standard_GS3,Standard_GS4,Standard_GS4-4,Standard_GS4-8,Standard_GS5,Standard_GS5-8,Standard_GS5-16,Standard_L4s,Standard_L8s,Standard_L16s,Standard_L32s.\\r\\nFind out more on the available VM sizes in each region at https://aka.ms/azure-regions.\",\r\n \"target\": \"vmSize\"\r\n }\r\n}"}]}

Start by locating the Ubuntu Gnome deployment template and its VM size setting; compare the configured Standard_D2 with sizes available in UK South. Validate the template by checking that deployment succeeds in that region, and confirm the chosen size is supported there.

Written by the indexing model from the issue text.